Cleaner Wrasse (Labroides dimidiatus)

The underwater world has an abundance of different and unique wonders. The phenomenon of the cleaner wrasse is a result of symbiosis (sharing life) which I believe is very characteristic of life under the water. Two are better than one.

We do not know for sure how the cleaner wrasse started to clean and care for its ‘patients’, but we are sure that the basis of the cleaner wrasse phenomenon started with a one-time incident that took place millions of years ago.

The cleaner wrasse, a member of the labridae family, is the size of one of our fingers; its body is light in color and it has a dark stripe the length of its body. It is one of the more interesting fish on the coral reef, but also one of the more cunning ones.

If, on one of your dives, you happen across a crowd of fish gathered around a certain area of the reef, you have probably come upon a ‘cleaning station’. At the cleaning station, the cleaner wrasse is cleaning and caring for its ‘patients’ using its mouth, which is adapted to controlled plucking/tearing off of parasites, and sharp eyes that are capable of locating even the smallest of parasites.
Parasites: microscopic crustaceans capable of sucking blood.

At each cleaning station you will find a pair of cleaner wrasse, but in the more dense areas it is possible that every station may have a different number of cleaner wrasse. The cleaner wrasse invites its patients through a dance that indicates its intentions and the reliability of the service that it can provide to all fish. The service includes finding parasites, tidying scales, removing damaged skin and cleaning any remainders of food from between the teeth of the fish.
From the moment that the cleaner wrasse starts its dance indicating that the station is open, the fish gather and often they can be seen waiting in a queue for their turn. When their turn comes, often the recipient indicates the area that is infected by lifting its fin, moving its tail around, opening its mouth, etc . . .

The carnivores do not wait in line; when they arrive, the queue disappears entirely, including whichever fish was already being treated, and the cleaner wrasse quickly turns all of his attention to the ‘new client’. Here we witness something that is amazing; the cleaner wrasse goes in and out of the predator’s mouth without fear, and removing remainders of food from its teeth.

This process is called symbiosis: based on the joint relationship between two creatures that both benefit from this association. The cleaner wrasse benefits from the association by earning both food and protection. The cleaner wrasse feeds on those same parasites, food leftovers and bits of damaged skin that he has actually removed from his ‘patients’. These parasites are small, and studies have shown that the cleaner wrasse feeds on up to 1200 parasites daily. In exchange for this service he also benefits from protection from predators.

Another phenomenon is imitation.

The mimic fish that takes advantage of its similarity to the cleaner wrasse and establishes similar cleaning stations. Through a dance which is identical to that of the cleaner wrasse, it invites other fish to be cleaned. The fish, who are used to the cleaning routine, give themselves to the mimic for treatment. The mimic fish takes advantage of their lack of caution, bites a chunk of their flesh, and flees into the reef. This is one of the reasons that fish are wary of new cleaner wrasse fish, and unfamiliar cleaning stations. With the opening of the new station the cleaner wrasse announces the presence of that new station – “a cleaner wrasse is here” – by dancing energetically and through a spectacular swimming performance. The reef fish congregate but do not approach for cleaning, and are waiting for the ‘hero’ that will approach to examine / for the first cleaning. The cleaner wrasse knows that the satisfaction of the first patient will ensure that he has work (food).
But this is not the only reason.

It is also a fact that the cleaner wrasse is known to sometimes be deceitful.
What happens if there are no parasites on the fish? Does the cleaner wrasse remain hungry? Not exactly.
It is known that the cleaner wrasse sometimes deceive their clients when they are hungry by biting the flesh of the fish. The cleaner wrasse does this cleverly, and never if there is a queue at the station, in order to prevent other ‘patients’ from fleeing.

Who cleans the cleaner wrasse?
Cleaner wrasse clean each other.
The cleanup task is not limited only to cleaner wrasse and fish. There are several types of long-abdomen crabs that do the work of the cleaner wrasse to eliminate parasites. Also, there are several species of fish that serve as cleaner wrasse when they are young, and by doing so they ensure their survival.

The cleaner wrasse indicate a behavioral connection that can develop between a large number of species and can result in extensive shared behavior that enables partners to live together better. The amazing ability of the cleaner wrasse to get along with and live in harmony with a large variety of reef fish indicates successful social relationships. On a healthy reef there will be a large number of continuously operating cleaning stations.

During my recent dives in the Gulf of Eilat, I have witnessed a decrease in the number of cleaning stations on the reef. The reason for the decrease in the number of cleaning stations is a direct result of a decrease in the number of reef fish. Over and over again we observe damage and pollution that have occurred from a variety of factors that indiscriminately damage the Gulf, and its enchanting underwater marine life. The future of the Gulf of Eilat, and the life therein, depends on us humans. Only through cooperation amongst the various entities and the enforcement of laws will we be able to preserve the Gulf of Eilat for future generations.

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

Rays are undoubtedly one of the most interesting, extraordinary and strange creatures that live in the sea. A flying carpet, a stealth bomber, a giant bat . . . these are just some of the nicknames people use when they see them for the first time. Rays are flat fish that belong to the same family as sharks and have also evolved as sharks. Unlike other fish, sharks and rays have no bones and the skeleton is composed of cartilage, which is weaker than bone but has the advantage of flexibility and resistance against diseases.

Stingrays typically lead a social life, and they are to be found in all the oceans.
Most of the cartilaginous creatures have venomous spines at the base of their tail. These spikes are for protection only and can cause sharp pain to inexperienced predators. When it stings, the tip is broken and remains inside the body of the victim, and can cause a number of infections. Anyone who gets stung will suffer from acute pain and possibly from necrosis at the point of injury and in extreme cases, death. Their greatest enemies (except for humans) are their relatives, the sharks.
In addition, some of them have long tails that resemble a whip and these are equipped with formidable spikes, and some of them have short tails.

Rays can be seen in sandy areas, coral reefs and open water.
Of all the species that live in the sea, this is undoubtedly one of the most interesting species, including some of the most bizarre-looking creatures, which are for the most part shy, but some of them are also very sociable.

The species of rays can be divided into three different groups according to the regions in which they live, their body structure and their method of hunting:

Manta ray: spectacular and unique. They can be seen swimming in large schools of up to several dozen, in the southern part of the Red Sea. They live in open water, where they filter their food: plankton. The filtering action is performed by their network of gills; lobes that look like arms help by directing the water towards the mouth, and from there to the gills. These lobes are located at the front of the head and give them the appearance of a devil with horns. In the past the mantas had been attributed with qualities associated with bad luck and many sailors believed that bad luck would come to anyone harming them.

The plankton collection process looks like racing pilot demonstrating aerial performance. The manta identifies large concentrations of plankton called ‘plankton clouds’ and performs a lot of strange rotations within these clouds. The large body – over 6.5 meters, and enormous weight of up to 2 tons – is home for many creatures, including fish that accompany them everywhere.

Stingrays: the largest and most diverse group of rays. These fish are flat and round and have a long tail; their bodies are adapted to the areas that they inhabit – sandy beds. Thanks to their structure these camouflage artists manage to cause a swirl of water by flapping their “wings”, which lift sand onto their bodies so that only their eyes – which are set in the uppermost part of their head – protrude. Their food consists mainly of invertebrates living in those same sandy areas. Craters on the sea bed are often evidence of hunting areas. The mouth of the stingray is located on the lower side of the body, and its eyes are on the upper side, so actually a stingray cannot see its food, and it is only by using its sensors that a stingray can identify and catch its food from the sand. The tail is one of the identifying marks of the stingray – long and sometimes armed with sharp points along it, in addition to as many as 3 venomous spines at the base of the tail.

Some live in shallow water, for example the bluespotted ribbontail reef stingray, taeniura lymma, which lives mostly in shallow lagoons in the areas of the reef. While it searches for food it creates clouds of dust. It has sapphire-colored spots on its body, hence the name.

The marbled electric ray (torpedo sinuspersici) belongs to this group: it generates electricity using special organs in the pectoral fin. The electricity it produces helps it find and paralyze potential prey, which do not see the electric ray as it is usually completely covered with sand.

Spotted eaglerays – aetobatus narinari: excellent swimmers that live in the coral reef and on the rocky bottom. Their food consists of mollusks with they gather using a special tooth that is suitable for scratching the shellfish from its base, and by using strong teeth that are designed for cracking, which are located deep inside the mouth; these teeth provide them with the ability to crack the hard structure, remove the shells, and get a meal. They are up to 3 meters in size and the origin of their name is the way that they swim, which is reminiscent of a bat.

Some of the rays are particularly friendly: at Sting Ray City in the Bahamas, local stingrays have gotten used to coming to feeding grounds and tourists can hand feed them fish and invertebrates. Around the world there are several places where they can be hand fed. However, beware not to try and feed stingrays in the sea.

At the Underwater Observatory Park the stingray caregivers place the food into their mouths and take advantage of this opportunity for an up-close visual inspection of their body. In the shark pool one can see a spotted eagleray eating shellfish directly from the hands of the diver, and those with good hearing can actually hear the sound of the shell being cracked.

Nowadays, most of the danger to rays comes from humans – especially fisherman – and the destruction of habitats and hunting grounds.

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

In honor of Chanukah, the Festival of Lights, I would like to share with you the world of marine creatures which not only celebrate Hanukkah all year round, and for whom “light” is a way of life.
Bioluminescence – cold light produced by animals – is undoubtedly one of the amazing wonders of nature. Thousands of organisms and plants above and below the water can illuminate or radiate light in places where there is no light or they wait for the evening and night hours to shed their light. Some of these extraordinary animals use their light to signal to other animals or different species, some use it to attract a mate or to intimidate and confuse predators, while others use it as camouflage. And of course, bioluminescence also serves to illuminate, blind, and attract different prey.
Most organisms use bioluminescence to produce their light by a chemical reaction that takes place within special organs designated for this purpose. However, there are species which create light from the chemicals of other light organisms they prey upon. Within these light organs there are special bacteria which glow, and in turn cause the host to glow. These light organs have complex lenses, reflectors and a color filter which change the light according to different needs and utilize it to its fullest.
Deep in the ocean, there is darkness all year round. And it is here, in the depth of the ocean, that the largest and most amazing variety of glowing and illuminating organisms can be found.
Bioluminescence is used only by marine animals (saltwater fish).

Photoblepharon
As dusk falls, a Flashlight Fish slowly swims out of its hiding place between the rocks and coral reefs. Flashlight fish are afraid of rays of light and if the moonlight is too bright, they will immediately return to the security of the dark crevices of the reef. Flashlight fish use their impressive “headlights” to attract prey (mainly plankton and small crustaceans), to confuse their enemies by flashing their headlights on and off, and to communicate with each other.
Their glowing light is produced by large light organs located below each eye, containing millions of luminous bacteria that emit light while consuming sugar and oxygen from the blood of the Flashlight fish. The light organs have lids which help the Flashlight fish to control the emission of light by “turning it on and off”. These lids resemble eyelids, and their dark color prevents the penetration of light when the “eyelids” are closed.
The beam emitted by a single Flashlight fish is strong enough to enable it to see a distance of 30 meters at night; equal to the amount of light needed to illuminate a small room.
When a Flashlight fish is threatened by a predator, it “turns off” (closes the lid of the light organ) its “headlight”, darts away from the predator, and then turns the headlight on and off, while the predator tries to figure out where it is. In this way, the Flashlight fish manages to escape, leaving its predator blinded and confused.

How do the light organs work?
Light organs are called photophores. At least two chemicals are needed to produce the light. The first is luciferin, a chemical that actively creates the light, and the other is luciferase which develops the chemical reaction. As the two chemicals mix together with oxygen – light is created.
The army light stick is a beautiful example of how two chemicals are mixed together to produce light.

Comb Jellies
When people first see a Comb Jelly, they usually confuse it with a jellyfish, yet Comb Jellies belong to a different family than that of the Jellyfish. Comb Jellies are a family containing about 90 species, all of which are Comb Jellies.
Comb Jellies are transparent, which makes it hard to spot them and one can usually find them swimming underwater close to the shore. But Comb Jellies are also found in open oceans and the deep sea. They feed on marine organisms and tiny plants called plankton. Some Comb Jellies are cannibals and feed on other Comb Jellies, some swallowing them whole. Those that don’t swallow their prey, catch their meal with their sticky tentacles which slice the water like fishing rods. Comb Jellies that do swallow their prey intact have an elastic mouth that can stretch open to swallow creatures their own size. All Comb Jellies possess eight rows of “combs” that divide their body into eight even parts. These combs are made from Cilia (Comb Jellies are the largest creatures that use Cilia) and serve as arms which the Comb Jelly uses to propel itself through the water.
The Comb Jelly light show is both complex and wonderful. There are two types of light that characterize the Comb Jelly. One is called iridescence – a stunning phenomenon in which sunlight passes through the Cilia, refracting the rays of light which reflect back in a rainbow of stunning colors and shapes. This light is called iridescent color. This phenomenon can be seen in daylight and it is an unforgettable sight to watch. The second half of the light show is a phenomenon called bioluminescence, which is the cold light emitted from a special gland produced by the Flashlight fish. At night, when the comb jelly feels threatened, it turns on its lights and the night show scares away predators.

Glowing corals
Every time I walk into our dark room, here at the Observatory, the beauty of the glowing coral always excites me anew. Visitors often return to us specially to once again enjoy the brilliant coral display. Unlike other bioluminescent organisms which produce light, glowing coral needs light in order to reflect its glowing light. This phenomenon is called fluorescence. Within coral tissue there are proteins with fluorescent properties. When these proteins are exposed to light, they absorb it and release it back at a higher wavelength but with less energy. The proteins do this so as to utilize the energy differences of the light they reflect. There are certain fish that prefer to eat protein that has fluorescent properties and they have adapted themselves, with the help of infra-red light, to detect corals with special proteins. Glowing corals come in an abundance of shapes, sizes and colors.
Author: Aviv Levy – Scientific Director of the Underwater Observatory Marine Park

Jellyfish
Unlike the mythological Medusa (also the Hebrew name for jellyfish) which was able to turn every living thing she looked at to stone, the marine jellyfish does not have a negative effect on its viewers who are mostly charmed by its beauty. There are close to 200 different species of jellyfish. The smallest are no more than a few centimeters long while the largest reach huge dimensions, with a body more than a meter long and tentacles 40 meters long.

Jellyfish
The body of an adult jellyfish consists of a bell-shaped body made of “jelly” that envelops an internal structure from which tentacles branch out. In the center of the internal structure there is a mouth attached to an incomplete digestive system: the entry of food and the disposal of waste takes place from the same organ. Every arm is coated in sting cells called “nematocysts” that can paralyze or kill other animals. Most jellyfish use their tentacles to catch prey or to defend themselves.
The body of an adult jellyfish consists of 94% – 98% water and the remainder is salts, minerals and protein. No creature above or below the water suface is like the jellyfish. They have no vertebrae, bones, heart, brain, eyes, blood, fins or gills. They are equipped with nerve and muscle cells that help them “feel” the environment and their food, or sense danger and react to it through movement. Most jellyfish and their food are carried along by the ocean currents, the most common of these being the “upside-down” jellyfish, which inhabits the Red Sea. Jellyfish use vesicles on the edge of their bell to maintain balance and equilibrium. Sensory cells help them know if they are rising or falling in the water and help them distinguish between dark and light. They do not have a hydrodynamic shape which makes them slow swimmers, but speed is not important since they are carried on the current and feed on plankton.

Life cycle and reproduction
Most jellyfish change their shape in two stages during their life cycle. The first is the polyp stage: The jellyfish takes the form of a trunk fixed to the seabed which catches food or other moving organisms that move with the current.
In the second stage the Jellyfish takes on the form most people are familiar with – an umbrella-shaped body called a bell, with tentacles hanging from its edges.
The jellyfish goes through four different developmental stages and change their shape after each stage. These four stages are: planula larva, budding polyp, ephyra and medusa.
In most cases, the male releases sperm into the water column and the sperm swim into the mouth of the jellyfish where the egg is fertilized. After fertilization and initial growth, larvae covered with tiny hairs develop from the egg and roam in the current until they find a suitable hard substrate to settle on. After settling, each larva develops a polyp, which resembles a sea anemone. There is a growth period of between several months to several years, during which time the polyps multiply and form identical colonies built of discs that sit one on top of the other. In the next stage the discs, called ephyra, are released into the open sea where they grow tentacles and a mouth and become young jellyfish.

Eating and defense
The tentacles of most jellyfish, some of which extend from the mouth, are covered with thousands of sting cells. These cells contain a capsule with an external trigger. When the trigger is touched it releases a sting which pierces the skin of the victim and injects venom. If the victim is a suitable meal, the jellyfish will pull the prey into its mouth.
Although most jellyfish do not endanger humans, there are some species, mainly in the region of Australia which can seriously harm humans and in extreme cases cause death.
Many sea creatures feed on jellyfish, mainly turtles and fish.

On the menu

A salad of jellyfish with sesame and sesame oil and, occasionally spring onion, is a customary first course in the Chinese kitchen. Vietnamese dishes also include jellyfish, but with hot peppers. Koreans serve jellyfish with sweet and sour sauce and a mustard base.

Treatment of stings
A jellyfish sting can cause burning, rash, irritation and even death.
The jellyfish along the coast of Israel are not deadly, and in most cases their sting only causes temporary burning and redness of the skin. The Australian box jellyfish is the most poisonous creature in the sea and possibly the most venomous on earth.
Sting treatment has three purposes: to prevent the person who treats the sting from getting stung, to deactivate the sting cells and to remove jellyfish tentacles that may be stuck to the skin.
Whoever treats the sting must avoid contact with the sting cells by wearing protective clothing and gloves. You can deactivate the sting cells by applying vinegar to the area of the skin which has been stung. The vinegar neutralizes the venom mechanism and prevents further injection of venom into the body. Tentacle residue must be removed from the body with tweezers or a similar device, so that whoever is treating the sting doesn’t get stung himself. In any case, the sting must not be rinsed with fresh water or alcohol as they cause the release of more venom into the body.

** In the “Life in the dark” presentation, you can view a presentation of our new Moon Jellyfish.
In the discovery room at the Underwater Observatory Marine Park there are aquariums of upside-down jellyfish which live on the seabed, have a unique appearance and live their life sharing with algae and crustaceans. Teams of divers feed the various jellyfish every day at 11:30.

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

Many people have heard about the hatching of Hawksbill sea turtles here at the Underwater Observatory Park, but few know the complexity entailed in a process the beginning of which is hard to predict and where the success of the release is only known in the future. I was one of those privileged to have the opportunity to actively participate in all phases of a new generation at the observatory, from preparation through breeding and brief encounters on the high seas.
We will follow the growth and release of turtle “5 red” (the names will be explained below).

Hatching date: 28.08.1999
Hatching weight: 17 grams
Shell length: 4.2 cm
Shell width: 3 cm
Health status: good

The process began at the beginning of the February 1999. In preparation for the mating season, we isolated Zachary, a male Hawksbill turtle. Zachary had lived for a year in the adult turtle pool, shared by the females Hawksbills. The purpose of the isolation was to change Zachary’s orientation to cause a kind of “nostalgia” for the female turtles. At the same time, we checked the sand in the island of the adult turtles’ pool. The composition of the sand plays a major role when female turtles dig their nest. The sand must be damp to some degree, so that the future mothers are able to dig a nest and lay their eggs.
The second step is the hatching period. Moisture, density, composition and salinity are all factors that determine the state of the sand.
We found the sand unsuitable, so it had to be replaced. After two months of isolation and the replacement of sand on the island, it was time for Zachary to return to the females in the main pool. The day he returned I was anxious. Where two months in isolation enough? Were the females ready for mating?
In the wild, the Hawksbill turtle lives in permanent territories, with each female occupying an area of a few miles along the reef. Each of these female “plots” is dominated by a male.
Breeding begins in the spring, when the male impregnates the females in his territory. Adult male and female turtles can be easily distinguished by the length of their tail; the female’s tail is short, the male’s long. However, when turtles are young, this distinction cannot be made, the reason being that puberty lasts between five to seven years and only then is the difference in tail size evident. In extreme cases a blood test can be done to identify the gender.
The big moment arrived, and without delay Zachary was placed back in the pool with the females. Funally “let loose”, Zachary pounced on the female turtle, Tyson, and bit her neck. But there was nothing to fear, this is a natural part of courtship and mating. (Tyson got her name after biting the ear of one of the divers, Gadi, a short while after boxer Mike Tyson did this to rival Evander Holyfield.). At this point, Zachary “sat” on Tyson’s back with his front limbs hugging her hard shell close to her neck, and his back limbs hugging the side of her shell. Stuck to her shell in this way, he started mating.
At this point, the female must carry the male, whose full attention is on mating and not swimming. Hawksbill turtles belong to the family of marine reptiles which spend most of their lives in water. However, they breathe air above the surface through the mouth and must come up for air every few minutes. The ability of turtles to hold their breath is interesting, and while resting, they only need to surface every half hour. Yet when active, such as catching prey or mating, they need to surface more frequently. So denying them their privacy, we all looked on with expectation as Tyson carried Zachary on her back for the next four hours.
As we continued to monitor the activity in the pool over the following days, Zachary maintained his strength and impregnated the remaining females in the pool.
At this point, there is nothing more to do but wait for the egg-laying season, which takes between several weeks to several months, due to the female’s ability to retain sperm, and she will only fertilize her eggs when she feels ready.
For the next month, we daily examined the state of the sand in the island, and wet it from time to time so as to maintain the required moisture level. We also raked and smoothed the sand every day so we would know if Tyson had been to the island to start digging.
I tried to dig a nest with my hands the size and depth of a turtle nest. This is a great way to simulate the female experience of digging. I dug a nest relatively easily, and if I had succeeded, then maybe Tyson would follow suit.
“Tyson is digging,” the urgent message came through while I was eating lunch. I immediately went to the adult turtle pool. Indeed, Tyson was busy digging her nest in the center of the island. Digging a nest requires much effort. Adult females in nature do not always manage to return to sea after spawning because they are exhausted from the effort and in a few cases they eventually die. This did not happen in our case because we were able to help Tyson return to the water. We watched as Tyson dug with her hind feet, and with each dig, one of her feet served as a kind of spade that removed the sand from the hole. After an hour of digging, Tyson had completed building the nest. (Was it fatigue or dissatisfaction with the sand?) After a nerve-wracking 10 minutes – bingo, Tyson began to lay her eggs. I was so happy and from a distance observed the nest slowly filling with eggs. At first, the eggs came out in pairs and then one by one. By the end, there were 55 to 60 eggs in the nest. Tyson covered the nest with sand and camouflaged the area to prevent potential predators from identifying its location. This task can be compared to a child in a sandbox who throws the sand in all directions.
Once she was done, Tyson tried to regain her strength and return to the water. After a 10 minute rest, she crawled back into the pool.
At this point, Tyson had completed her role as a mother and would have no further contact with the nest or her babies. We marked the location of the nest for future examination.
For the next two months the nest received the required heat from the sun for the eggs to develop. The sun actually incubates the island. The time of spawning is important and needs to be in early summer to ensure the nest is exposed to the sun during the warmest period. Here in Eilat, the hot season is exceptionally long and therefore the timing is less important than elsewhere in the world, where if even a few days are lost, the eggs in most cases will not hatch.
During the next two weeks, the other female turtles climbed onto the island, dug a nest, spawned their eggs, covered the nest and returned to the pool.
Again, we needed patience and I couldn’t wait until the hatching season.
At the beginning of the hatching season we prepared the island for hatching. A low fence was built around the island to prevent the young turtles from reaching the pool.
The night watchman gets ready for hatching, and most of his time is spent monitoring the island.
A midnight call woke me up and Shaul, the watchman, shouted into the phone, “We’ve got turtles, we’ve got turtles.” I gave out a long screech and woke my wife. “We’ve got turtles, we’ve got turtles,” I shouted, repeating his words. Without delay, we made our way to the Observatory and immediately gathered the turtles in a special container prepared in advance. We counted 43 in all – an outbreak of turtles!

Newborn turtles leave the nest in a group. The first turtles to hatch climb to the top of the nest and stop at a waiting point for the remaining turtles to hatch and join them, before seeking the sea. The reason for this is the fear of potential predators on land and in the sea (birds, crabs, small mammals and fish are just some of the predators). By departing the nest together, the turtles confuse predators and increase their chance of survival. Studies and observations carried out in nature show that only one in every thousand eggs reaches adulthood.
We head home, happy and tired.
The first thing I did the following day was to uncover the nests on the island, because sometimes some of the turtles don’t manage to leave the nest with the others. I dug carefully and discovered a turtle among the eggshells that had hatched but hadn’t made it out of the nest. I placed it in the container along with its siblings.
We began taking care of the turtles. First, we marked the turtles to enable us to monitor each one individually. Turtles have a hard heart-shaped protective shell made of 13 overlapping plates. Using different colored nail polish, we marked a plate on each turtle with a number of 1 to 13. The turtle I dug out of the nest was named “5 red”. While marking the turtles, we gave it a general examination: skin, eyes, claws (Hawksbill turtles have two claws on each forearm that are used to cut food) and tail. Then we weighed each turtle and daily updated their data on the computer. To our delight, all the turtles had a normal weight of between 16 to 21 grams. For the first few days, the turtles fed on protein leftover in their bodies since spawning. The turtles are isolated to prevent the spread of infectious diseases and biting. Each container had a water spout. After a few days, the turtles started to eat from our hands. Their food was a special mix of fish, vitamin-enriched invertebrates and fish oil. Feeding was carried out with tweezers three times a day and we recorded each feeding on a special table so we could identify problems early on and treat them. We were also able to monitor the turtles’ eating habits and growth.
At 4 months old, the young turtles were transferred to common pools. Individual monitoring continued thanks to the markings. The turtles were now being weighed once a week and their diet changed to pieces of fish, jellyfish and invertebrates served on the pool surface. This way, the turtles learned to dive and use their claws to cut food. The turtles lived in this common pools for a year before being released at sea.
Recent years have seen a drastic drop in the number of turtles in the Gulf of Eilat. In cooperation with the Israel Nature and Parks Authority, the Underwater Observatory Marine Park initiated a project for the raising and release of Hawksbill turtles in the Gulf.
When preparations for the release of the turtles began, the team was filled with excitement, anticipation, trepidation and a feeling of satisfaction. A microchip was injected into the hind leg of each turtle which will remain there throughout the turtle’s life and will enable it to be identified in the future with a chip reader. The turtles were thoroughly examined before release. Only the healthy ones would be released into the open sea. The markings on the shell were highlighted to enable remote identification. Spring is usually jellyfish season and young turtles usually feed on jellyfish, so releasing them in the spring promises the young turtles a rich food environment during their initial adjustment to the sea.
The big moment arrived. We collected the turtles in special baths and loaded them onto a boat named “Pearl of the Corals” The release was entitled, “I have a turtle in the sea.” The turtles were releases at three locations in the Gulf of Eilat: the coral reserve adjacent to the Underwater Observatory Marine Park, the Trans-Israel pipeline area, and the shores of Jordan.

A team of divers from the Underwater Observatory Marine Park entered the water and observed each turtle in the sea. At the last release in Jordan, a team from the Aqaba Green Initiative joined us because we share the Aqaba-Eilat gulf.
A total of 90 turtles were released into the sea.
Turtle “5 red” was released on the shore adjacent to the Underwater Observatory weighing 3.150 kg.
7 months later our paths crossed – following an observation of the coral beach reserve, turtle “5 red” was caught and brought to the observatory for examination. It weighed 4.250 kg and was in good health. After the examination, “5 red” was released back into the sea. This was followed by four subsequent meetings, the last of which took place in May 2004, when “5 red” weighed 7.5 kg. At every meeting we found “5 red” in the coral reserve and therefore nicknamed it “Turtle Reserve”. When I dive in the Gulf, I find myself looking for “5 red”, even for a fleeting moment.

Hawksbill turtles are endangered worldwide. Fishing, pollution and vulnerability in the nesting areas as well as a decline in the quality of sea water are key factors in their disappearance. Mistaking them for jellyfish, turtles accidently eat plastic bags which block their digestive system and can cause death. Working together to maintain nature’s values will ensure the continued existence of turtles in the Gulf for future generations.

The Raise and Release Project of Hawksbill turtles was carried out in collaboration with the Israel Nature and Parks Authority.

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

The two things I love the most are the sea and sleeping.
Last Saturday, for example, I was at the beach from morning till night and when I returned home I got busy with my second hobby, and went to sleep. As you’ve guessed, sleeping is really important to me. I have my own blanket (Mom says it’s time to replace it, but I will not give it up! I’ve had it as long as I can remember, and we’re firmly bonded …) I have fish-patterned pajamas and when I go to bed I ask not to be disturbed and fall straight asleep.
Yesterday, I woke up in the middle of the night because I thought of my friends in the sea and was concerned about them!
What about all the fish, do they sleep at all? They must be so tired. I kept tossing and turning and couldn’t sleep the whole night.
Early the following morning, I went to my parents’ room and asked them if fish sleep and if they have beds. I wanted to know how many hours sleep they need, and so on…
My dad didn’t know what I was going on about at such an early hour, and mom asked me to start from the beginning. Dad was convinced that my fish pajamas were to blame, and suggested buying me some new pajamas – without fish. I started blabbering on again and made it clear that under no circumstances was I going to replace my pajamas or my blanket! Mom laughed…
“I have an idea”, said Mom. “Why don’t we go the Underwater Observatory Park and ask Meirav, the girl who takes care of the fish in the aquarium.”
Not a bad idea, I thought.
“That’s an excellent question,” Meirav said, excitedly, “and the answer is yes, fish do sleep!”
That’s lucky, I thought to myself.
“But before I explain about sleeping underwater, perhaps you can tell me why we need to sleep at all?” Meirav suggested.
I wasn’t sure of the answer…
Meirav continued, “Just as people get tired at some stage, fish do too,” she explained. “Ever night I have my sleep routine: I get into pajamas, jump under the blankets, close my eyes, and go into a state of rest – I fall asleep. When we sleep, our bodies also rest: our muscles relax, our breathing is slow and steady, and we hardly move, just toss from side to side.
That’s just like me, I thought.
“Rest is very important,” Meirav continued to explain. “Most people sleep an average of eight hours a night which means that one-third of our lives are devoted to sleep and rest …
“Fish need to rest too,” she continued, “and while most researchers are not sure if fish sleep deeply, or just take a nap, I’ll tell you about some fish that have found original ways to rest. Fish also use pajamas and in some places they are used as a bed.
“Fish with pajamas?” I asked, and immediately jumped up, imagining fish pajamas with people on them. “It’s a different kind of pajamas,” said Meirav. “Fish change their color before they sleep, usually to red, because red is difficult to see in the sea at night. One of the most beautiful examples of a fish that changes to red is the lunar fusilier, a blue fish that swims in schools and changes its color to red when it rests. Fish can change the color of their bodies by contracting and expanding pigment cells in the skin, and in the case of the forsskas goatfish, the body color changes from silver with a yellow stripe to red and white…
The lunar fusilier and forsskas goatfish sleep on the sand – this is their bed. The exquisite butterfly fish, however, prefers to sleep among the corals that hide and protect it from night predators. In addition to the hiding place and the arms of the coral that serve as bars, the exquisite butterfly fish can change its body to the colors of the sea as camouflage! Better safe than sorry ….”
“The truth is that not all fish wear pajamas,” Meirav continued. “Some fish bury themselves in the sand, like the orange wrasse which tends to sleep in a permanent place. Before nightfall, you can see the wrasse cleaning and arranging the area it sleeps in.”
“Just like you,” Mom laughed and added, “Before you go to bed your covers and pillow must be in place….”
“Mom … you’re embarrassing me,” I whispered in her ear and carried on listening to Meirav.
“After the wrasse prepares its bed, it buries itself in the sand where it rests until dawn. Because the wrasse is hidden by the sand, it doesn’t need to change color at night. Sometimes in the morning when it wakes up, it lifts its head from the sand to see if there is danger nearby, just as we peek out from under the covers. The Itretail hogfish combines camouflage with hiding. It hides in alcoves, cracks and even sponges (animals reminiscent of coral) during sleep. ‘Good night’, it says to her when it goes out on a night dive ….”
I feel a bit jealous – I also want to dive at night.
Meirav goes on, “Carnivorous fish that swim in the dark hours have large eyes and well-developed vision,” she explains. “But hunting at night in the dark is not easy and predators must use their sense of smell to navigate. Many fish have found a solution to this problem by locking themselves inside a sleeping bag! Apparently some fish, such as parrotfish, secrete special mucus from their mouth which surrounds the body like a bubble. This protective bubble serves as a kind of scent camouflage because the smell and secretions that are emitted from the parrotfish while it sleeps do not escape the bubble and cannot be detected by predators. Cleaner fish also uses a kind of sleeping bag, every night in the same place. When the cleaner fish awakens in the morning, it removes the bag from the area so that predators will not discover its nightly hiding place.
It is important to remember that many fish hide among the corals during sleep and therefore any harm to the corals leaves these fish defenseless against predators.”
Meirav invited us to go down to the Underwater Observatory to observe how the night predators rest during the day. In the caverns surrounding the observatory we saw sunfish, grouper fish and even goggle eye fish that were sleeping and hardly moved. No fish dares go near these predators! They do not need to change color, bury themselves in sand or hide in a sleeping bag, and the alcoves and caverns provide relative peace and reduce the amount of light. Soon, as darkness falls, they will open their eyes and nostrils and set out to find the same sleeping fish.

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