Akwarium Gdyńskie

Order: Myliobatiformes
family: Whiptail stingray

Taeniura lymma

The Bluespotted ribbontail ray, a representative of cartilaginous fish, is common in the Indo-Pacific from southern Africa to the Solomon Islands, including the Red Sea. This is the most common stingray among coral reefs. Interestingly, adults and adolescents live in different habitats. Adult stingrays occur in deeper reefs (up to 20 meters deep), while young prefer warm, shallow waters with a bottom covered with seagrass, mangroves or covered with rocks, where they find shelter from predators. The Bluespotted ribbontail ray grows up to 70 cm in length with its tail being half of this length. The maximum width of her body is 30 cm. Its main food are annelids, small molluscs, crustaceans and cephalopods, which it finds by combing the sandy bottom. In this way, it plays an important ecological role as a bioturbator by modeling bottom morphology, and also determines the density patterns and distribution of benthic infauna (organisms living in bottom sediments). It hunts mainly at night, and spends the day still.
T. lymma has a characteristic blue dots on the back, and the tail is distinguished by blue stripes on both sides. At the end of the tail are two sharp venom spines that are used for defense. They are remnants of skin teeth that covered the body of stingrays. Lost spikes grow back and the wounds inflicted by them are very painful. It is a ovoviviparous species. During courtship the male bites the female. Pregnancy can last from 4 to 11 months depending on many external factors. Such a long pregnancy makes them more susceptible to the collapse of the population. Fortunately, these rays are able to breed in captivity.

Atractosteus spatula

The Aligator gar looks like something between a pike and a crocodile: a lengthened trunk with three fins in the tail part refers to a pike, and long, toothed jaws are associated with a crocodile. The Aligator gars do not take care of their offspring. They are the largest freshwater fish in North America and may exceed the length of 3 m and the weight of 100 kg. They hunt for large prey, not only for other fish, but also for lizards, snakes and turtles.

It is one of the most primitive and the largest freshwater fish species in the world. Fossils from the Cretaceous period (145-66 million years ago) have been found in America, Europe and Asia. Currently, their natural environment are lakes, rivers and reservoirs in central and northern America, however, their number is constantly decreasing due to overfishing and dams, which prevent reproduction. They reach huge sizes, grow up to 200 cm on average and the largest specimen caught was 305 cm in length and weighed 166 kg. They can live up to 50 years. From time to time, the fish is observed to swim under the surface of water to get extra air, which makes it easier to survive in a low oxygen environment. It is possible thanks to the vascularized bladder connected to the pharynx. Female may deposit 138,000 eggs at a time. The eggs are bright orange and unfit for consumption, as they are poisonous. The Alligator gar has two rows of teeth and the internal row is longer. This feature allows to catch and effectively hold the victim in the mortal grip of strong jaws.

order: Perciformes

family: Acanthuridae

Paracanthurus hepatus

The only representative of the genus Paracanthurus.

The Blue surgeonfish is found in the coastal waters of the Indo-Pacific Ocean, from the coasts of East Africa to Oceania, excluding the Red Sea. It has a wide extent of occurrence, but is not common. We can meet it, among others, on the coral reefs of the Philippines, Indonesia, Japan, Australia, New Caledonia, Samoa, as well as Sri Lanka. It is associated with coral reefs, it lives mainly near their outer parts, where sea currents are stronger. The extent of occurance is related to its love of swimming. It inhabits coastal waters with a bottom covered with vegetation. It can be observed at depths from 1 to 40 meters. Its maximum length is 31 cm, but they usually grow up to 20 cm. It can live up to 30 years in the wild, and 8 to 20 years in captivity. Its food is comprised mainly of zooplankton and algae. Juveniles feed exclusively on plankton. It is a very important inhabitant of the reefs, because he cleanses corals of algae growing on them, thus keeping them in good condition. Most often, this species lives in pairs or form small groups of 8 to 14 animals.

Its characteristic feature is its coloration, blue body with black back and yellow fins. The attractive colors makes it a popular aquarium fish. Until recently, all individuals that we could admire in aquariums were caught directly from their natural environment. Currently, this species is successfully propagated in laboratory conditions, but not on a global scale. The larvae differ significantly in color from adults. Their body is almost transparent and silvery. It gradually turns blue, yellow pigmentation appears at the very end of development. At night its blue color pales, presumably avoiding the attack of nocturnal predators. Another characteristic feature of the Blue surgeonfish is the presence of sharp, poisonous spikes located on the tail, one on each side, which are used for defense. It is not of great commercial importance, but it can account for a significant proportion of inshore fisheries.

Its meat has an unpleasant smell and is poisonous. After ingesting it, the symptoms of food poisoning may occur.

This surgeonfish does not produce a toxin (ciguatoxin) by itself. It is accumulated in its body along with the consumed algae that produce toxin.

Why is it blue?

The fish do not have blue pigment in their skin. The blue color that we can see is nothing but a light phenomenon. Isidophores, i.e. pigment cells that reflect light, are responsible for this phenomenon. In the light they create iridescent colors, but by proper orientation of the schematochromes (prism-like structures, refracting and dispersing visible light to the surroundings,) and using biochromes (biological pigments) as a filter, they create a blue color.