Spanish Dancer – Hexabranchus sanguineus

Very few divers have seen a Spanish dancer dancing; those who have had this opportunity immediately understand the origin of its popular name. The source of its scientific name is Hexabranchus sanguineus from the Latin, Hexabranchus = six gills, and sanguineus = blood colored. This marine dance is reminiscent of the famous flamenco dance, including the body twists, exactly like the gypsies who started dancing in this folkloric style hundreds of years ago.
The Spanish dancer belongs to a group called “sea slugs” (basically snails without shells). The dancer spends most of its time crawling on the sand at the foot of the reef in its search for its favorite food – sponges: these are primitive creatures, living in a fixed place, nourished by filtering small food particles in the water – the filtering is performed by using both an entry, and an exit filter. The dancer can be found in depths of up to 50 or more meters, a depth that most divers do not reach.
The dancing slug can be found anywhere from the tropics to the Indo-Pacific. The Spanish dancer was first identified in the Gulf of Eilat in 1828 by Ruppel and Leuckart. It is one of the largest in its group, and it reaches a length of 40 cm; a few even reach a length of half a meter, or more. This naked snail has six external gill clusters in the rear section of its body. It retracts, and extends its gills from a type of centipede formation that protects the gills. Here too, one notices the fascinating similarity between dancers above, and below water: the gills extend in the same manner as “La Gitana” (the flamenco dancer) waves her fan marking the start of the dance. The dancer has hornlike formations on the front of its body that act as feelers which the Spanish Dancer uses to “smell” the water, and find its favorite food. The Dancer’s eyes, which are more than likely used to find a mate, are situated at the base of these horns.
It feeds mainly on poisonous sponges which it eats while it crawls slowly along the sea floor, leaving a trail of gnawed crumbs.
The Spanish Dancer can be identified by the color of its bright red cloak, and its edges, which are white in some species. In most cases, it is difficult to identify the dancer when its cloak is closed. In certain areas of the world, especially Hawaii and Tanzania, they can also be found in shades of yellow.
The sophisticated dance performance can only be seen when it is escaping from predators. When this slug feels threatened, it swims with a twisting body motion that helps it to maneuver towards a safe haven in the water. The Spanish Dancer received its name because of its fascinating swimming movements. Very little is known about the reasons for its bright colors, most researchers agree that the colors are a warning sign to other fish that they are toxic. In this case the warning is applicable, since while eating the sponges it produces venom made from the different toxins in the sponges with which it protects itself, and its offspring. The Dancer’s eggs are protected from predators by the self-defensive venom inside the egg.
The slug’s similarity to dancers does not end here: the eggs it lays resemble the orange / red lace that gypsy dancers used to add to the hems of their dresses.
In every batch, there are thousands of eggs from which the young slugs hatch. In the initial stage they swim until they change their shape, after which they settle on the seabed, and become young slugs. In principle, all slugs are all hermaphrodites, meaning, each individual has both female and male organs. Despite their ability to self fertilize, in most cases, they prefer donating, and receiving sperm to maximize the diversification of their genes. Sometimes, by looking closely, one can see small crustaceans that live on their bodies, feeding on the food particles that stick to the mucus covering its body. These crustaceans have a red color that makes it difficult to identify them on the slug’s body, and this also serves to protect the crustaceans from predators for most of their lives.

Author: Aviv Levy – Scientific Manager, Underwater Observatory Marine Park

While most of the visitors at the Underwater Observatory Park observe the magnificent animals and their unique world, a small group of people on the side watch the work of animal caregivers, responsible for taking care of the animals at the site.

The group will begin its tour in the kitchen area, although from the smell, it’s obvious where they’re headed before they arrive. Gal and Shiri are preparing food, the likes of gourmet cuisine, for the hungry animals. Octopuses, squid, shrimps, sardines, tuna, oysters…. are all part of the daily diet. Special emphasis is placed on cutting the food: strips of squid and octopus for the eels (except for the Moray eel, Ezmeralda, who was hit in the jaw during a courtship battle and can only eat food cut into small pieces), small squares for the trigger fish, diced tuna for the lobsters, minced shrimp for the sea goldie, whole fish for the sharks, clams for the spotted eagleray, small sardines for the stonefish … We monitor the feeding of all the different animals to make sure they all eat and to identify problems early on. We have three feedings a day. The emphasis is on preparing food according to their natural dietary needs and, so we match the size of the food to mouth size. “This is a squid’s head,” explains Gal, “considered a delicacy among eels. Feeding at the aquarium begins at 11:30,” he says, inviting us to join him. Next stop: the treatment station. Here we see Idan and Eric get ready for diving. “We’re going to treat the observatories,” says Idan. “Every day we clean the windows, dust and treat the corals, check the pumps, and so forth. Today the emphasis is on searching for predators. Animals, such as snails and slugs feed on the corals, so we spot the damaged coral and then look for the predators which in most case we find, and then we remove them from the coral with special tweezers.” Shay also prepares to dive. “I’m going into the shark pool,” says Shay. “We go into the shark pool every day to feed the sharks, monitor their feeding, and to clean and treat the pool. I wear a special mask that that allows me to speak and hear underwater, so that I can explain to the public about the sharks and answer questions as I dive and feed.” While diving, Shay wears no protective clothing. His protection is his experience and his understanding of the world of sharks. We wish Shay good luck and make our way to the turtle hatchlings pool, where Shiri begins the daily checks and treatments. “The turtles are five months old and I have been with them since they hatched here at the observatory. First, I look for any inflammation on the skin, nose and eyes. I then check the turtles’ shells and remove any algae that have grown. After that, I weigh and measure all the turtles to make sure they have gained weight and are growing well. ‘They’ve all gained weight nicely’,” declares Shiri. “Turtle seven red has a slight eye inflammation,” continues Shiri while she cleans pus from the eye and smears some anti-inflammatory cream on it. “Some of these turtles will be released into the sea in the future to try to help the existing wild turtles who are in danger of extinction. The big turtles were born here thirteen years ago!” It’s now 11:30 and we join Ron for feeding at the aquarium. Here there is the stonefish, the most poisonous fish living on land and looks like a stone. “Stonefish eat whole fish which I put on the end of this stick, says Ron. He places his stick with a sardine on the end of it into the aquarium and gently moves the stick from side to side so that the sardine looks like it is swimming. Then, without warning the stonefish leaps and swallows the whole sardine. “The octopus lives here,” says Ron, pointing to an aquarium fully covered with mesh. “The octopuses can climb out of the tank, and there have been cases where they got into the neighboring aquarium and ate the fish.” The octopus is not a fish; it belongs to the family of shellfish and is a shellfish that learned to swim. The octopus is very intelligent and needs to be stimulated with games and challenges. Every morning while cleaning the tank, the caregiver dedicates some time to morning games. The octopus receives its food in a corked bottle, and it must open the cork and remove the food from the bottle. Ron opened a bottle, put in a large shrimp, closed it and put it in the aquarium. The octopus stretched out two arms, took the bottle, opened it, pulled out the shrimp and put it in its mouth. We continue our tour and come to a room with many aquariums of different sizes. It is actually a lab that contains an isolation room, a delivery room, a marine animal hospital, a nursery, a habitat for the young, a sanatorium, and more. “Here we have young seahorses that were born last night,” Ron points out proudly. The male seahorse gets pregnant and is the only male animal in nature that can be certain he is the real father. In the spring, the mating and spawning season is at its peak and many fish get injured fighting for their breeding rights. We also have a lionfish on a diet. It was living in an aquarium with other lion fish and it ate all the food! Here in isolation, we can control the amount of food it eats. Even for fish, overeating is unhealthy and can lead to complications and in extreme cases, death!

Author: Aviv Levy – Scientific Director of the Underwater Observatory Marine Park

Venomous creatures are an inseparable part of reef life. There is a constant, round the clock struggle for existence. In recent years we have witnessed a considerable decrease in the number and quantity of the various species of fish and invertebrates. In this struggle for existence the balance has been breached, and venomous creatures are not immune. Like dominoes that collapse one after the other in a chain reaction, marine life is also in danger of extinction and, once the process begins, it is very hard to stop it. It is enough for a single species of fish or invertebrate to disappear in order to affect the entire food chain; something which could have disastrous results on the entire ecosystem.

In nature, it is well known that the ability to defend yourself is a matter of life or death. Speed, strength, camouflage, deception and sophistication are some of the traits by which marine creatures survive. But creatures that are not equipped with these traits have been given venom.
There are about 1,000 marine creatures which are venomous. The topic of venomous creatures has always been filled with mystery, rumors, exaggeration and fantasy. Here we will try to put some order into this ancient subject. As long as 3600 years ago, the Egyptians tried to find antidotes against the venom of poisonous creatures, and also tried to describe a small portion of the creatures that are responsible for this damage.

As a child in Eilat, I remember the first time that I wanted to go into the water. My parents forced me to wear sandals. Of course I was very angry, but I was not yet familiar with the dangers that are lurking, awaiting ‘bare feet’.

Marine conus textile

With most venomous creatures, the venom is only a form of self-defense. The conus textile, a beautiful marine gastropod mollusk , is one of the exceptions to this rule; the conus textile uses its venom to paralyze its prey before eating it. The venom is located inside the venom gland which is connected by a harpoon-like tube which the gastropod shoots to its prey from its proboscis. The darts are produced inside a special sac and are stored at the front of the sac, ready for firing. The conus can shoot one dart each time, and simultaneously a new dart gets placed into the shooting position. Upon impact the end of the dart breaks and the venom inside it bubbles its way into the victim.
I’ll never forget the story about the poor fellow who wasn’t familiar with the venomous conus, and saw one for the first time. All he wanted was a nice memento from the Red Sea, and he collected the conus inside his swimming trunks. It is unnecessary to mention the pain and embarrassment on his face when he arrived at the ER and tried to explain the strange thing he had done.

Lionfish / Devil Firefish – Pterois miles

The Lionfish is a most beautiful predator and, as its second name indicates, certainly is a ‘firefish’. This is an active night predator with 13 very sharp spines on its back, with a venomous gland inside each spine. When pressing on the spine (swallowing by a predator, or touching by a human) the venom is released from the gland in the spine into the body of whatever has touched it.

The venom causes a sharp pain, often also swelling, but soaking in warm water dissolves the venom. When the firefish identifies danger it erects the spines in the direction of the danger and is ready for any possible confrontation. The firefish have beautiful and bright colors which can be seen from a distance, and it is these colors that also emphasize the spines, by which the firefish announces to everyone ‘I’m poisonous – you’re better off finding prey elsewhere’.

Striped eel catfish (Plotosus lineatus)

This is rare fish that lives in the southern part of the Gulf of Eilat – the venomous striped eel catfish, which reaches a size of up to 32 cm. When they are young, they live in schools of hundreds and as adults they live alone or in a school of a few dozen. The striped eel catfish has a venomous spine on the outside of each gill, and another venomous spine on the first dorsal fin.
The venom is located at the tip of the spine and results in terrible pain. In recent years a number of these fish have been found in the Mediterranean Sea.

Rabbitfish (Siganus rivulatus)

The rabbitfish – or, by it’s popular name, ‘venom’ – is a common fish, a vegetarian, and has a row of spines along its back which are covered in a venomous texture; when touched (often when attempting to throw a rod) the poison penetrates into the body of whatever has touched it.

Reef Stingray (Taeniura lymma) – Catfish

Catfish belong to the family of cartilaginous creatures and are very similar to sharks. At the base of its tail there are three venomous spines. Whenever it is in danger the catfish turns its tail so that the spines are visible and prominent.
These spines are particularly poisonous when they are touched and the tip of the poisonous spine is broken, so that the venom remains in the body of whatever touched them. Touching one can result in terrible pain, necrosis and inflammation due to the tip of the spine remaining inside the body. Catfish are shy and prefer to run from danger rather than use their venom.

Fire Coral – Millepora dichotoma

Fire Coral is part of the coelenterate system – marine stingers which are not true corals at all. These coral are found on the reef in shallow water and have stinging cells that they use to paralyze their prey. The name fire coral is justified in this case because, if touched, one feels a really strong sensation of being burned, and in extreme cases this can even result in the formation of blisters.

Upside down Jellyfish – Cassiopeia

Cassiopeia – ‘Upside Down’ jellyfish – live in shallow lagoons. They have stinging cells called nematocysts; when the Cassiopeia feels threatened it immediately releases these stinging cells into the water. The nematocysts are composed of capsules that are closed with a ‘door’; outside the door there is a spring clip that opens the door and pushes the spine through it, releasing poison into the threatening entity.
When this occurs, not all of the nematocysts open – in order to prevent those unopened cells from opening it is best to pour vinegar (antidote) onto the area.

The Sea Urchin – Asthenosoma varium

A venomous mechanism can also be found among the sea urchins. The poisonous glands of the sea urchin, which has a very intense color, has four different types of spine – the first, which is also the shortest, is used for protection: the venomous glands are located at the end of these spines and these are the only ones that contain venom. It is not the penetration by the spine which hurts, but the poison that is injected.
The second set of spines provides camouflage, and they are used as grasping rods with which the sea urchin can cover itself. The third set is used to help the sea urchin walk.
The last set of spines is used to help the sea urchin remain inside the crevices of the reef, which is where it hides during the day.

Orange Sun Coral – Sp. Dendrophyllia

This beautiful coral is probably the world’s most photographed coral and at a glance it is easy to understand why. The sun coral uses its stinging cells to protect itself, and also when paralyzing its prey. In contrast to reefs which need light in order to exist, the sun coral does not need light, and it must hunt for all its food. Its tentacles have clusters of stinging cells with which it hunts for its prey. Upon touch, the stinging cells burn and trap the food. During the night the sun coral spreads its tentacles and captures zooplankton to feed on.

In conclusion

Marine creatures that carry venom use it both for attack and for defense; there are a lot of them and their poisonous mechanism is both complex and interesting.
Sometimes fish / coral which appear to be innocent can cause a sensation of pain and burning. In order to avoid touching these and others, we should remember that we are visitors in the sea, and should not disturb their peace by trying to touch them.

Written by: Aviv Levi – The Scientific Director of the Underwater Observatory Park.

We are all familiar with the terrifying story of Captain Nemo’s submarine which sailed into the depths of the ocean and was suddenly captured by a monstrous octopus which threatened to sink it. The resourcefulness of the captain prevented the terrible tragedy. People often wonder if the account of the giant octopus which can encircle a submarine and threaten to sink it, is a true story or just a great fairy tale for children.

Evasion under an ink cloud
Octopuses are the cleverest and most interesting of all the marine creatures. They belong to the mollusk family which includes animals without a supporting internal skeleton such as the snail. But unlike the snail, which is supported by an outer shell, octopuses have neither a skeleton nor a surrounding shell. Every octopus has eight tentacles which it uses to move along the sea bed and over the rocks of the reef. Each tentacle is covered by tens of suction cusps each of which has strong adhesive power.
There are a number of ways the octopus can defend itself against danger, the primary one being the ejection of an ink cloud, emitted from a sac full of black ink located in its body. In times of danger the octopus squirts ink into the water and escapes under cover of the resultant thick, dense and murky cloud. The octopus can eject a number of ink clouds before the ink sac is completely emptied. Apart from the ink, using special pigment cells found in its skin, the octopus can camouflage itself perfectly well by rapidly changing its color to that of its surroundings. In addition, by creating protrusions and changing the texture of its skin, the octopus can change its shape and size, remaining so well camouflaged that one can pass by and not even notice it.
With the help of its sharp eyesight, the octopus can identify a predator from a great distance before being identified. At that instant it freezes on the spot, its color blends into the surroundings and its eyes contract until the danger passes. When in danger, octopuses excel at rapid swimming but only for very short distances. They do this by creating a forceful burst of water which propels it forward, a movement reminiscent of a jet engine.

Together and Separate
Octopuses are not particularly social animals and every octopus has a habitat which it guards jealously even from its own species. However, despite being solitary animals, every year one can see pairs of octopuses spending a few hours together. This occurs in the mating season – spring, during which the male octopuses begin to move along the length of the stony sea bed in search of a female. Upon meeting another octopus they carefully examine each other from a distance, checking out the other’s size, and the males confirm that it is indeed a female opposite him and not another male. After the examination ritual and the establishment of a suitably sized couple, the two of them settle on a stone. The male extends his breeding tentacle embellished with a small number of attachment cusps, and from his mantle (body cavity) removes a sac containing sperm, which he passes into the mantle cavity of the female. The reproduction process takes a few hours and while it takes place the two octopuses sit quietly, glassy eyed, and oblivious to their surroundings. Large grouper fish exploit these opportunities and more than once can be observed trapping an octopus during the reproduction process. After passing the sperm sac to the female, the couple hastens to separate before one of them develops an appetite.
After fertilization, the female octopus begins to look for a suitable rock den. Once found, she enters the aperture and over a few days seals the entrance with coral fragments and shells. All attempts to open the den of the female octopus are met with stubborn resistance and no fish is able to penetrate.
The female lays a large number of eggs, up to a thousand per batch, then protects and ventilates them in fresh water to prevent bacterial and fungal infection. The safeguarding period of the eggs lasts about 50 days, during which the eggs develop and hatch under the watchful eye of the mother. At the end of this period, when the young octopuses leave the den, the life cycle of the female is usually over and she dies. The tremendous amount of energy expended in building the nest, laying the eggs and guarding the young octopuses at the start of their lives, saps the energy of the female, who does not feed during this period. In most cases, female octopuses do not manage to survive after the end of the reproduction season, whereas the males survive two and even three reproduction seasons. Only one or two of the hatched octopuses will survive till maturity, the majority being eaten by fish and crustaceans in the first stages of their lives.

Sophisticated Hunting Mechanism.
The diet of the octopus is mainly comprised of fish and crustaceans with the hunt usually taking place in the early hours of the morning or when the sun is about to set. The octopus has a highly developed sense of sight and can see sharply and clearly over a long distance. Octopuses like settling on a branching stony coral which it envelops with its tentacles. From time to time, by extending a tentacle into the branches of the coral and utilizing its suction cusps, the octopus traps one of the frightened coral fish. Usually it does not hunt like this alone, and is joined by a large grouper fish and an adult lionfish. These fish swim alongside the coral and catch any poor fish which, having managed to evade the octopus’s tentacles, is trying to find shelter in another coral. On the other hand, they also help the octopus in its hunt because upon seeing them, the coral fish hesitate to leave the coral branches. In this way, with its suction tentacles, the octopus manages to catch the fish and bring it into its sharp, strong parrot-like beaked mouth. The octopus rarely sees its prey. Its eyes, situated high above its head, scrutinize the surroundings spying out predators, whereas the tentacles are busy searching for food.
There are many different species of octopuses in the world: the largest reach a length of up to seven meters, and the smallest octopus at maturity is no longer than a centimeter. In Australia there is a small species which lives in shallow water, and which in addition to its camouflage ability, has a very potent poison. When the octopus is held, it simultaneously bites and injects its poison which can kill even an adult. In order to warn predators and keep them away, the octopus is covered in bright blue circles acting as warning colors. But by bad luck this color attracts the eyes of small children, and more than once children have been injured by the poisonous bite.
So are there really giant octopuses of the size described by Jules Verne? As far as we know such enormous octopuses do not exist, though there is a species of giant squid, the colossal squid, (a relative of the octopus family), whose tentacle length can reach up to 20 meters! It is known that whales, who feed on deep sea squid, rise not infrequently to the surface of the sea with signs of a struggle in the depths of the ocean covering their body.
So maybe the story of giant octopuses is only a legend, but octopuses are without doubt one of the most interesting creatures living in the sea.

The Underwater Observatory Octopus
At the Underwater Observatory in Eilat one can learn about the high intelligence of octopuses and their learning ability. There, one of the aquariums is dedicated to the adult octopus. In consideration of the solitude which he likes, the aquarium is for him alone. Because the octopus is by nature a curious animal and enjoys stimulation and cognitive assignments, the underwater observatory challenges him with different activities. The food of the octopus is offered to him in a closed bottle with a screw lid. In order to get the desired food, the octopus must open the lid, put his tentacle inside and draw out the food. Octopus feeding takes place daily at 11.30.
So are there really giant octopuses of the size described by Jules Verne? As far as we know such enormous octopuses do not exist, though there is a species of giant squid, the colossal squid, (a relative of the octopus family), whose tentacle length can reach up to 20 meters!
There are a number of ways the octopus can defend itself against danger, the primary one being the ejection of an ink cloud, emitted from a sac full of black ink located in its body. In times of danger the octopus squirts ink into the water and escapes under cover of the resultant thick, murky cloud.

Coral reefs are the center and foundation of the ecosystem of the tropical oceans. Without reefs did not exist at all rich and wonderful world this.

Dependence on the reef is not only under water, even over the water the reef is the physical basis on which entire nations are built. Also, without the reef there was no physical space on the reefs they created human beings created a rich world cultures, and other social and religious heritage is a product of living water – the reef. Other countries coral reefs contain large and complex that providers millions of people every day. Tropical reef abundance of proteins is the basis of the daily menu of tens of millions of people. The reef also provides a natural breakwater for the coast guard. Most of the reefs can be found mainly in poor countries, and millions of people from rich travelers and vacationers in poor countries economically, but rich in coral reefs. Economic importance of coral reefs is very high, and sometimes also the basis of most of the local economy and the introduction of foreign money. Coral reefs are living systems, the richest and most complex in the world. Both the house of not less than one million species of living things – plants, fish, worms, clams and more, who have complex relationships between them. But one day a prominent importance in building the reef – a polyp. Coral’s body called a polyp, and they secrete around themselves like a rock skeleton Girni. Rock / skeleton This is the key to all the world’s reefs. The majority of the world’s coral reefs survival is threatened. Some of them are even real danger of extinction! Although there are natural threats, the greatest danger that threatens coral reefs of our activity – human beings. But not too late to help the reefs. Submitted a list of issues which anyone can help: A. Support businesses that help keep your reef. Two. Not to use pesticides with chemical additives (a large part of these materials end up in the sea or our water sources.) Three. I volunteered to clean above and below water. Four. While visiting the coral reef make sure all the local bylaws. Five. Spread the word: You can save the reefs. 6. Make consumers aware of, to be part of the industry’s global maritime memorabilia. Seven. Do not pollute! Dirt on land eventually reaches the sea. Eight. Recycle, by less spam reaches the sea. Nine. Save water. 10th. Report any illegal activity affecting the beaches and reefs, responsible bodies need all that extra pair of eyes. 11th. Keep it clean There’s no shame to collect other people’s junk. 12th. While visiting the reefs around the world use local guides. 13th. To be anchored on the reef, used corks off for anchorage. 14th. While diving is no touch, no Lharhif sand and keep the reef clean. 15th. Volunteer organizations that help in maintaining the reef. 16th. Support the creation of nature reserves. 17th. Educate yourself, learn and learn how you can help passing laws designed to protect the reef. Millennium report shows that in recent decades destroyed 20% of coral reefs, and the chance Lhtaossotn unreasonable. In addition, 70% coral reefs were reduced to some extent, especially in the Caribbean and parts of Southeast Asia. Most severe deterioration process occurs in developing countries, where are most of the coral reefs.

Author: Aviv Levy – Scientific Director of the Underwater Observatory Marine Park

23 Jan

Have you ever wondered how fish manage to be buoyant in water all day, and still have the energy to take care of their needs? A buoyant, or a well balanced body, invests minimum energy to remain deep in the water, because a buoyant body requires less motion energy under the water than a weighted […]

My first encounter with the butterfly fish was in a laboratory during a summer seminar. In a jar filled with formaldehyde lay a beautiful fish, decorated in amazing colors, its elegant display of color frozen in time forever.

Until that encounter, I never knew that butterflies also existed in water, but its colors revealed the fact that they are named after terrestrial butterflies.
Terrestrial butterflies have a short life span, and their breeding only continues for one season – sometimes, with casual partners, and other times in mass orgies with millions of other participants, or more.
This is where there is no correlation, in fact quite the opposite, between butterflies above, and below water.
Butterfly fish establish long term relationships, usually for most of their lives. The couples look after each other, and do not change partners for their entire life. Long term commitment is the key to living together, helping each other to survive on the reef for many years. Breeding only takes place with the same partner every year, although sometimes the fish change their sex, and breed as opposites.
The butterfly fish family is undoubtedly one of the most beautiful and colorful fish families, with a flattened body structure that is perfectly adapted to their coral reef living environment.
Reefs function as a spawning ground for the thousands of animals that live in this environment for most of their lives. Their flattened bodies enhance their sharp movements, and delicate maneuvering between the coral, flapping their relatively large fins to fade between, and above the coral in their search for food. Their color, plus the manner in which they flap their fins, and their darting movements from place to place, are reminiscent of both the color, and reveling movements of terrestrial butterflies.
Their food consists of crustaceans, worms, mollusks, anemones, and coral, which is the most important in order to understand the butterfly fish’s existence on the reef. The butterfly fish is able to successfully eat coral by using its small round mouth, situated at the end of a type of short trunk. The butterfly fish bites the polyps upon which it actually creates its resting place on the coral.
There are 114 species in the butterfly fish family, 14 of them can be found in the Gulf of Eilat, 7 of them are indigenous (live in a certain region) to this area. The butterfly fish usually socialize on the reef as a couple, or sometimes as an individual. The butterfly fish can be observed on the reef throughout their life: maturing, eating, sleeping, defending, courting, and breeding – which is as integral part of reef living. Besides the coral the butterfly fish also feed on sea anemones, during which you can observe the cat and mouse games in which they are involved. The anemone lives together with the sea anemone, and is responsible for protecting it from predators – the butterfly fish.
The butterfly fish’s colorful patterns drive the anemone fish crazy, causing them to attack the hungry invader. Experiments have proved that there is a connection between the butterfly fish’s show of color, and the anemone’s behavior, regardless of shape. We, as scuba divers diving along the reef, are also used to the harassing actions pursued by sea anemones in defense of their hosts. Another phenomenon that exists among both terrestrial and marine butterflies is the use of their color patterns to camouflage the eye area, and to create a “false eye”. The butterfly fish are not equipped with special defensive measures (speed, armor, poisonous spikes, etc.). However, through the use of color, and sophistication, the butterfly fish succeeds in being deceptive, and blending in with its colorful environment. The eye is the key to survival, or rather hiding the eye, by creating stripes, and stains around the eye region in order to camouflage it, and usually the eye participates in the deception with the colored patterns that are formed on the eye.
Predators usually attack their victims’ heads, as a head injury is supposed to paralyze its ability to defend itself, and escape. The predator focuses its attack on the eye but this is not straightforward when it comes to butterfly fish. Trying to locate the eye / head area causes the predator to delay its attack, giving the victim sufficient time to avert the attack and escape.
Another method of deceiving predators is by using a false eye, creating an image of an eye in the rear tail, or fin section which succeeds in confusing the predator. This confusion causes the predator to focus its attacks on less vulnerable areas where the healing process is much faster, enabling the fish to survive its injury and heal – being bitten on the tail is preferable to being bitten in the head. When a spouse is injured, one notices the devotion and commitment the butterfly fish couple have towards each other. During the injury period the spouse will guard, and protect its partner, and its territory.

Author: Aviv Levy – Scientific Manager, Underwater Marine Observatory Park

Blenniidae Kingdom

In the shallowest water, where it is impossible to swim, we find the ‘Blenniidae Kingdom’. So who, in fact, is king of the first ten centimeters? If you ask me then, without a doubt, this is the cutest of all fish, the bright ruler who learned to live right on the sea shore. With good sight, and commanding his entire kingdom, he has found
a sophisticated way to cling to the rocks while most of the other creatures are swept away by the waves.

If you asked someone more knowledgeable than me about blennies, you would probably hear about a large family of over 300 species, all scaleless, with two thorns in their dorsal fins. All of this is apparently very interesting, but that is not why I lay on my stomach for hours in very shallow water in the Gulf of Eilat, entirely captivated by the beauty of this small fish. Primarily it is the small protuberances over the eyes that look like eyelashes. These are to be found just above the intelligent eyes that stare me with awareness, examine me and trust me. They decide that I probably do not constitute any danger. The fish allows me to come close, and remains two inches away from the camera, allowing me to snap a royal portrait. When the tide begins to rise, the blennies invisibly harvest algae and appear to be very engrossed in this work. There are types of Blenny that leave the water altogether, above the waves. They can do this by using the water that remains on their skin, which keeps them from dehydrating in the hot sun.
There, above all of the dangers lurking in the underwater world, the blennies and other creatures – such as crabs, shrimps, snails and limpets – feel safe.
If you put your feet into this warm and friendly water we will find them nibbling our feet while our little friends display interest close-up: sea bream, a silvery fish that competes with the rabbit fish for the best areas of algae. Crabs are uncertain where it is safest for them – above or below the water: sometimes they compromise and sit with each half of their body in a different ecosystem.

Now that the dangers of being in the water have been dealt with, it is possible to concentrate on dangers from the air, such as sea birds whose shadow alone freezes the little ones into kind of sleep . . .. . They all freeze and wait for the bird to choose its victims; or has evolution taught the fish and crabs that birds do not excel at catching prey that doesn’t move? Whether this is the result of intelligence or fear – it works well, together with a little camouflage and matching colors, the little creatures seem to manage just fine.

Giving it some deeper thought, perhaps the behavior we are observing is the first hesitant step of marine creatures getting used to life on dry land. Is this possibly a picture of our evolution from marine creatures into terrestrial organisms, just as we are now able to return to the ocean, equipped with cameras. Are we looking at our past? Or could we be looking into our future??

Aviv Levi – Scientific Director of the Underwater Observatory Park

Every few years, following an exceptionally low tide, it is possible to see the sandy bottom of the reef exposed above the water line. The explanation for this unusual phenomenon is the low tide cycle: a phenomenon during which the height of the sea ‘rises’ and ‘falls in a fixed cycle. The first person who realized there is a connection between the cycle of tides and the moon was the Greek explorer Pytheas. The tide cycle occurs twice a day. The time between one tide and another is 12 hours and 24 minutes, due to a combination of the rotation of the Earth around itself, and the orbit of the Moon around the Earth.

On the shores of oceans in different parts of the world the difference between peak low tide and peak high tide can reach up to 8 meters. In the Mediterranean Sea and the Gulf of Eilat the difference is much less, due to the fact that these are seas are enclosed; in the Mediterranean it reaches half a meter, and in the Gulf of Eilat slightly more.

Corals that protrude from the sea during extremely low tide are damaged, and some of them even die (the bright white color of coral usually signifies that it has been damaged), but this is a natural process through which room is created so that young coral can settle. The degree of damage to coral and to creatures on coral reefs and in lagoons also depends on the wind: when there are strong winds in the Gulf of Eilat they cause waves, which preserve the moisture of the coral tissue, and fresh water flows into those same lagoons at the bottom of the reef. It must be remembered that there are hundreds of species of invertebrates that live in the lagoons amongst the corals and the fish.

On days of extreme low tides when there is no wind waves can be created by boats, thus minimizing the damage. Extreme low tides can be seen twice a year, at the end of the summer and at the end of the winter. Typically, due to the heat, the reef is damaged more during extreme low tides in the summer.

Corals are an endangered species; they grow between from 2 mm to 2 cm a year.

Aviv Levi – Scientific Director of the Underwater Observatory Park

I saw a shark !! I saw sharks !! a pair of shiny gray fins slicing through the water. I became alarmed and immediately my heart rate jumped, I froze on the spot where I was standing on a rock, up to my waist in the water, not moving. The sharks, in perfect unison, rose again ahead of me, and this time I realized that the edge of their fins is dark. They’re swimming about 50 cm from each other, coming in my direction. I’ve been swimming in the area for three days now, snorkeling and enjoying each and every of the strange and wonderful creatures. I’ve no one to call for help – my parents are diving in the area and should be up soon. I decide to swim to the shore as quickly as I can, three, two, one . . . and again, in perfect coordination, the sharks change their direction and dive into the water, disappearing. I put on my mask and put my head into the water quickly, but saw no sign of the sharks, or of my parents!! I started worrying. I searched around, only fish, swimming lethargically around, trying to find food that has been caught in the flow. And then, bubbles of air rising from the depth of the water – how great! My parents return and I see my mother about 5 meters below me. I accompanied my parents through the water to the shore, while all the time examining my parents to make sure they’re not missing any body parts, while the air bubbles are rising and bursting and tickling my stomach. On the shore I told me parents excitedly about my frightening meeting and my worries about them.

Now, over 25 years later, I know that there was no danger at all except for a heart attack! The sharks were “Black Fin” sharks – an average size shark that doesn’t grow to be larger than 1.8 meters. It is a reef shark that is easy to identify because all its fins are black around the edges, and hence its name. Only the underside is white. It is not considered dangerous to humans, and while looking for other food (fish) they come into the waters of the Coral Reef and even above the reef during low tide. This is exactly what happened then on the Sinai coast, and I was sure that they had come there because of me, whereas,, in fact, it was because of me that they fled from an area they normally inhabit.

My second meeting with the rulers of the sea occurred about two years later. The Virgin Islands, where my father had been sent to work, became my new place of residence. When I completed my diving course I looked for a way to dive as much as possible. I met a local fisherman who fished while diving. When I asked if I could join him he hesitated, and said that I had no experience. I ran a persistent campaign to persuade him, and added that I had already swum with sharks at home, in the Red Sea. The fisherman laughed when I told him about my first meeting with sharks, but he agreed that the next day I could accompany him on his dive.
Happy and confident I went to prepare my diving gear, and presented myself at ten to six in the morning, the time we were to leave.
We sailed to one of the nearby islands, cast anchor and descended into the water. I didn’t pay any attention to the fact that the fisherman had brought with him a large piece of a barracuda fish.
It all happened fast, fast and immediate. We’d gone under with the fisherman leading and I behind him. Within minutes a yellow shark appeared, swimming in circles slightly above the sand in the direction of the fisherman. I tried to yell to him that there was a shark in the water but, of course, he didn’t hear me, but my shouting did make the diving regulator fly out of my mouth. Then the fisherman removed that same piece of fish flesh, and held it out towards the shark. I became frightened and nearly forgot to breathe; I replaced the regulator in my mouth while the shark started to eat from the fisherman’s hand. I looked around and, right next to me, there was a small cave; I went inside with only a small part of my head peeking out towards the fisherman. Then, there was shadow above me. I looked upwards and really froze – a huge tiger shark was passing above me and swimming in the direction of the fisherman. When he saw him, the large shark pushed the rest of the slice of meat towards the huge shark – which swallowed it whole, swam around for a while, and then disappeared. The fisherman motioned to me to come to him, but I was scared of going out into the open water, and it was only after the fisherman came to me that I got up the courage to leave the cave, swimming directly to the boat. I got into the boat with my diving equipment with no problem, which should have been difficult due to the weight of the equipment, but due to the actual circumstances I literally jumped out of the water on to the safe deck of the boat. The fisherman got out of the water after me, and told me to relax – while I started speaking with him in Hebrew which, of course, he didn’t understand at all, and he was smiling . . . a smile which spread over his entire face.

The first shark had been a Lemon Shark, a yellow-grey sand shark, the color frm which it gets its name. Its head is round and it lives in the region of the Coral Reef. It is usually up to 4 meters in size. It feeds primarily on fish that it hunts on the Reef. It is considered dangerous to humans, and is also considered one of the more ‘intelligent’ sharks.

The second shark was a “Tiger Shark”, which lives in the upper regions of the body of water. They can be up to 7 meters long, and are one of the more dangerous fish. They feed mainly on fish and marine mammals. Diving with the fisherman, Tarwa, was undoubtedly a dive that changed my life. Since then I have been fascinated by sharks, try to learn about them at every opportunity and am always looking for opportunities to dive with them. Over the years I dived another hundred times with Tarwa, and nearly every time we spotted sharks.

During my first dives with sharks I always felt that, by a miracle, I was saved from attack; I didn’t understand why they didn’t attack me but, slowly, I got to know them, their modes of behavior, their preferred foods, their body language and, most important of all, I learned to appreciate one of the most wonderful animals, albeit one of the most frightening.

It’s hard to speak of sharks without mentioning the film “Jaws”. This film brought a lot of money to its producer (Steven Spielberg) but resulted in global fear of sharks, which continues until now. After this film was screened the shark was perceived to be a marine monster lurking everywhere waiting for swimmers and divers, and feeding delightedly on us humans.
This film and others, without a doubt, are the primary reasons for people being afraid of sharks; for the most part, there is no just cause for this.
But the irresponsible hunting of sharks is real, and results in depletion of sharks in the world. Sharks have always generated frightening stories, legends, exaggerations, lack of knowledge, inaccuracies and of course fear. In truth, only part of that is justified.

Of all the animals that walk, fly, burrow or swim there are only few that have survived for the long term, and can be found in large numbers of shapes and sizes like the shark. The first evidence of sharks dated back two hundred million years. However, the most interesting shark lived 70 million years ago. This gigantic shark (Megaladon), was up to 30 meters in size! But like other huge prehistoric animals, it became extinct over time. This gigantic shark and others are the ‘forefathers’ of the sharks that live in current times.

There are 344 types of sharks that are divided into 8 species, ranging in size from 25 cm through 20 m (the whale shark). These can be separated into three primary groups: the sand sharks, the reef sharks, and the open water sharks. The sand sharks, which have flat bodies, live for the most part in sandy regions and, contrary to the other sharks which must constantly be swimming, the sand sharks are often seen laying motionless on the sand. Generally their mouths are suited to cracking invertebrates that live in the sand, and catching small fish off which they feed.
The Reef Sharks live in the Coral Reef region. These sharks are, for the most part, of medium size and fast, and they hunt their food by swimming quickly above and inside the coral reef, thus managing to surprise their prey. They are considered the ‘cleverest’ of the sharks. This group also contains the Lemon Shark (negaprion brevirostris) which I encountered for the first time at the Caribbean Islands. Professor Samuel Gruber from the University of Miami, who studied them for over 30 years,
is of the opinion that they are capable of making association and remembering, like laboratory rats. The Black Fin Shark also belongs to this group.

Open water sharks are the largest and fastest, and also include those that are a threat to man. These sharks must be constantly moving in order to breathe. They can be seen in the deepest waters, up to just under the surface level. They are excellent swimmers.

Sharks are fish that belong to the family of cartilaginous fish (chondrichthyes): the shark has a spine composed of cartilage vertebrae and not bone, unlike all other
fish (osteichthyes). As with fish, sharks also have scales, but these are placoid scales that are characteristic only of cartilaginous fish. The feel of a shark is smooth in the direction in which it swims, but against the swimming direction (from the tail to the head) the shark is very rough . . . the first sandpaper in the world was the skin of a shark! The natives in Hawaii were the first ones to use this.

The body of most sharks is perfect for swimming (hydro-dynamic) and it is not by chance that submarines and torpedo missiles are amazingly similar to the shape of sharks. Equipped with a tail, the sharks can swim almost unhindered by the water. The fastest shark of all is the Lamnidae Blue Shark (isurus oxyrinchus) which can reach a speed of 50 kph and more. This shark is also known as the ‘Mako’ shark.

In order to understand the behavior of sharks, one must first understand their sensory system. The sharks have the same senses as humans: touch, sight, smell, hearing and taste. Additionally, the sharks are equipped with another two senses, the sixth and seventh. The sixth sense is a sort of ‘distance touching’, thanks to two rows of holes, one on each side (the side lines). Though these holes the shark is able to differentiate waves of pressure that are created from the movement of other living creatures even from a distance of hundreds of meters. The seventh sense is a type of electro-sensor capable of distinguishing electric fields given off by all living creatures. In order to identify the electric fields the shark is aided by small apertures located in the front of the head, which are connected to special glands. These glands are called “Lorenzini’s ampullae”.

Sharks receive information from their sensory system and act accordingly. Mostly, sharks feed on sick and wounded creatures and thus their sense of smell, which is very well developed, can identify blood, the discharge of a sick or wounded fish, even at a concentration of one part per million. Another method that the sharks have of identifying prey is by the non-uniform way in which sick and wounded fish swim, which result in water movements that are identified by the side line of the shark as being potential prey. This feature of eating constitutes the importance of the shark to the marine world: while feeding on sick and injured prey the shark is cleaning the waters and acting like a ‘cleaner’. This is also the origin of the main problem between man and the shark – in most instances of attack the shark has become confused and wrongly identifies man as being an injured creature. These attacks are called “mistaken identification’ and usually, in an instance of these attacks, after the initial attack the shark realizes its mistake and disappears.

Of almost 350 different types of sharks, only a few of these are dangerous to humans. But most people are scared of all kinds of sharks, to the extent that they panic just at the thought of sharks. Without doubt the most recognized of all sharks is the Great White Shark (carcharodon carcharias), which is up to 5 meters long and has strong jaws that are filled with sharp teeth. In recent years, the Great White Shark has become rare, and has been declared as a protected species by many different countries.

Written by: Aviv Levi – The Scientific Director of the Underwater Observatory Park.