NMFRI Gdynia Aquarium

Animals

Slender seahorse

Hippocampus reidi

Order: Syngnathiformes | Family: Syngnathidae

It is a coastal seahorse species, which inhabits coral reefs, areas overgrown with seagrass and seaweed, river mouths, and mangroves, from North Carolina in the United States, through the whole Gulf of Mexico and the Caribbean Sea, to Southern Brazil. The young prefer shallow waters, whereas adults can live in depths up to 55 meters. The average lifespan is 2,5 years and its maximum length is 17,5 cm. They are predators and often wait completely still for prey rather than actively chasing for it. Their diet consists of crustaceans, such as shrimp, copepods, gammarids, but also ostracods and nematodes. The juveniles mainly eat insects and the eggs of mollusks and crustaceans. They are poor swimmers, due to their body structure, but they make up for that with their prehensile tails, which can grab onto many different objects. They are active during the day, but they stop swimming when night comes and clatch onto corals with their tails and stay there until sunrise. They most often lead solitary lives, but couples are not a rarity, they are also seen in groups of more than two individuals. When it comes to the coloration, it varies from black to yellow, red, orange and brown, with many white spots, mainly on the tail. An interesting aspect is how quickly they can change coloration to blend in with their surroundings.

Similarly to a chameleon, their eyes move independently, so one eye can look down, while the other looks forward.

As a monogamous species, they couple up for life. During courtship, the male impresses the female with quick color changes and swimming displays. Males take care of the eggs, and they have a special pouch into which the female lays eggs, which are subsequently fertilized by the males. Young seahorses hatch after two weeks. These juveniles are sustenance for large pelagic fish, such as snappers or tunas. The Gdynia Aquarium is proud to have been able to reproduce these seahorses.

IUCN Red List

This is a ‘near threatened’ species. The development of coasts has caused the loss and degradation of their natural habitats, especially mangroves. However, the biggest threat is through bycatching during artisanal and industrial fishing. This species is utilized in regional medicine, the production of jewelry, charms, and amulets, whereas living organisms are sold as aquarium fish.

2017-07-27
Green anaconda

Eunectes murinus

Legends about the deadly man-eaters, reaching monstrous dimensions, have often found their reflection in mass culture. Certainly they were the inspiration to create entertainment class B movies. The Green anaconda belongs to the subfamily boa (Boa). It is noteworthy that all anacondas are found only in South America and are viviparous.

The animal leads an amphibious lifestyle. This snake inhabits shallow, slowly flowing freshwater habitats, as well as tropical meadows and rainforests with dense litter. The Latin part of the name Eunectes comes from the Greek language and means “good swimmer”. On land it is slow and sluggish while in water it can reach speeds of up to 20km/h. The Green anaconda has pronounced sexual dimorphism. Males grow up to about 3 meters in length, while females rarely exceed 6 meters and these are cases mainly of captive individuals.

Anaconda definitely doesn’t hunt people. On the contrary. The folklore of indigenous peoples of Brazil and Peru considers this creature magical, which is why body parts are sold for the purpose of performing rituals and treating various ailments. It should be noted that this strangler is one of the few snakes whose body proportions in fact would allow human consumption. However, our body structure, and precisely the shoulder width and width do not allow us to join this reptile’s menu. All snakes in the world swallow their prey starting from the head, so especially for us, the Green anaconda would have to change its current hunting technique. If it comes to meeting a human, the snake will try to bury itself in the litter or mud, or run to the nearest water. If that’s not enough, it will shoot a smelly substance towards the attacker from the anal glands.

The Green anaconda, despite its deadly snake patch, is not really a threat to humans. Scientists agree that the population of this species, although still stable, requires protection. Shrinking habitats, caused by draining wetlands for arable fields and massive felling of forests cause that there is slowly no more place in the world for this snake. Hunting does not help in the condition of the species. Despite its longevity, strong anthropopressure, unfortunately, does not allow these reptiles to grow to a larger size in peace. If this continues the fate of the anaconda, it will inevitably turn out that we will only be able to admire six-meter specimens in zoos. Environmental degradation, as well as man himself, contribute to the fact that the impressive dimensions of this reptile are significantly reduced.

The Green Anaconda is included in Appendix II of the CITES.

2017-07-14
Yellow tang

Zebrasoma flavescens

Order: Perciformes | Family: Acanthuriade

This species can be found in the waters of the Eastern and Southern Pacific Ocean, around the Philippines, Vietnam, Papua New Guinea, Guam, Southern Japan, Micronesia, Hawaii, and the Marshall Islands. It is most prominently found in Hawaii, where it’s used as an aquarium fish. It inhabits regions with a lot of coral and lagoons on the edges of reefs. It is possible to find this fish anywhere from 20 to 40 meters below the surface, but it’s more common to appear around the 20-meter mark. Its sustenance is comprised mainly of algae that grows on corals and the seabed. It has the habit of cleaning the algae that grows on the shells of turtles. It can live longer than 40 years, and it can grow to 20 cm in length. It grows very quickly in the first years of its life; a two-year-old fish can already be 10 cm long. After reaching maturity at around 5 years, the growth slows down heavily. Females reach maturity earlier, at around 3-4 years of age, while males take 4-5 years. As a result, females tend to be smaller. It can be found alone, in pairs, or in small groups in the wild, but it doesn’t stay in those groups for life. It is aggressive towards other representatives of the Acanthuridae family. It’s a very active and curious fish during the day, and at night, it looks for shelter.

The body of the yellow tang has a characteristic vibrant yellow color, which pales during the night, and its sides develop a darker coloring.

Like other Acanthuridae, it has two sharp spikes at the base of its tail to protect itself or to help during battles for territory. It most probably does not have a poisonous gland next to those spikes. It is dioecious and egg-laying. Spawning occurs in pairs or small groups, and it’s tightly connected to the phases of the Moon. Males demonstrate interesting mating dances during spawning.

Daily travels of the yellow tang

There is a distinct division in terms of habitat between juvenile and adult fish. The juveniles inhabit the deeper regions of coral reefs, where they find shelter. After reaching maturity, they change their habitat to shallower regions, which have abundant algae growth and greater biodiversity. The daily migration of juveniles isn’t as extensive as the migration of adults, which can cover even 800 meters between their day and night shelters. They spend their day seeking food in the shallow (<10m) regions rich in algae, and at night, they look for shelter in the deeper parts of the reefs.

2017-07-06