Fabulous underwater inhabitants in amazingly detailed photos

Marine biologist and underwater photographer Alexander Semenov and his team are the driving force behind the Aquatilits expedition , which is due to film animals underwater and use its findings to popularize science. This summer the Aquatilits expedition is heading to the White Sea in the Russian Far North to shoot footage and take photos. “Our large ambitious round-the-world project is delayed due to costs. But we have smaller expeditions and projects that are just about to start. In October, we have a project in Italy and right now we are filming in the White Sea. And we are working on a book." - Semenov told RBTH. / Cyanea capillata pictured.

Cyanea capillata or Lion’s mane is the world’s largest jellyfish. Its dome can grow up to 2.3 m in diameter and its tentacles up to 36 m long! The common size in the White Sea is a 50cm dome with 7-8 m tentacles, but it looks wonderful. The Sea of Japan is home to some giant specimens.

Cyanea capillata's tentacles. These tentacles are dangerous and can burn human flesh. They are also almost invisible when stretched to their maximum length. After reproducing, they become “nude” and loose them.

It may seem odd, but jellyfishes feed on jellyfishes! Cyanea capillata eats various planktons, including other jellyfishes. Moreover, cyaneas are able to eat jellyfishes that are a little bit bigger than themselves. / Cyanea capillata feeding on Aurelia aurita.

Aurelia aurita or Moon jelly is a common jellyfish that lives almost in every sea all over the world. They can grow up to 60-80cm in diameter and there can be millions of them in some seasons, giving the appearance of a huge horde of moving jelly covering an area of several square kilometers of water. An epic picture. Aurelia is not dangerous at all, it has short tentacles with very weak poisonous cells that are deadly to small plankton, but not for humans.

Flabellina polaris is a rare and beautiful nudibranch living in the depths of the cold northern seas under the thermocline in absolute darkness. The species Flabellina polaris is the rarest of all, encountered only at great depth and by no means at every turn.

Flabellina verrucosa is a beautiful nudibranch sea slug that feeds on cnidarians: stalked jellies, actinias and hydrozoan colonies. They have a unique defensive system: the dangerous nematocyst cells of cnidarians are not digested, but Flabellina transfer them to special sacs (cnidosacs), the white ends of each papilla. Therefore, each sac becomes like a fort with artillery stolen from jellies and hydrozoans.

A very rare moment is depicted here: Flabellina verrucosas mating. When mating they touch with their right sides, where they have a hole inside which is the copulatory organ. As hermaphrodites, they exchange syngenesis components and both become impregnated, afterwards they swim away.

Clione limacina or Sea Angel is a wonderful mollusc. Evolution stripped Clione of its shell. Its snail foot developed into wings, giving this group the name “pteropods.” Their only food is other molluscs, known as Sea Devils.

Molgula griffithsii or Ascidiacea. They usually have an unactive life, feeding by filtrating small pieces or unicellular algae from water. They have a simple construction, making this small limpid animal see-through.

Bolinopsis infundibuliformis has oral cavities on the front part of its body, which make up half of its total size.

Anarhichas lupus or the Atlantic wolffish is a big and sometimes dangerous fish, which lives in caves under stones. You always can spot one if you find a few square meters covered with the broken shells of molluscs. The wolffish has powerful jaws to break hard molluscs, which is one reason not to mess with it — it can break a fisherman or diver’s finger. It can grow up to 1.5 meters in length, but the one pictured is quite small and young.