After about 15 years of diving at the Biological Station on the White Sea in Russia, marine biologist Alexander Semenov has learned more than most about which jellyfish stings are the worst. If you accidentally touch the yolk jellyfish, for example, it doesn’t matter, he says. And while you should try to avoid a lion’s mane jellyfish, if you see a sunshimmer illuminate even one of the jellyfish’s up to 150 thread-like tentacles in front of you, it’s too late. “The next moment these tentacles just go to your lips and it hurts,” says Semenov.
These are the dangers of documenting the strangest forms of life that float, flutter and pulsate through our oceans – not to mention the brutal cold. The day he spoke to Scientific American Semenov had just been in 35 degrees Fahrenheit water, which felt warm compared to the 30 degrees F diving temperatures of the past few months.
Semenov accepts everything and even keeps visiting places at certain times to find the aquatic life he is looking for. But to him, no part of his job feels like an exercise in patience. “I just love all this stuff,” says Semenov. “And I can spend months and years in the same place, diving and searching.”
Venus belt, a type of comb jelly or ctenophore. Usually invisible, this gelatinous creature shimmers when disturbed. It curls up to protect its stomach (purple horizontal bar) and neural node of predators. “Fish have to eat a lot of slime before they get to the center,” says Semenov.
Mediterranean dealfish: The species swims vertically and lets its non-functional caudal fin drift behind it. If the bright purple dome and delicate scraps of tissue sound familiar, this is the point: the goal of the Mediterranean dealfish is to confuse prey that it is a jellyfish.
This comb jelly harbors a hyperid flea shrimp (pink ground with black eyes on the right). These parasitic amphibians burrow into their host’s stomach, sometimes in so large numbers that the victim looks more like a sieve than a jellyfish or ktenophore.
Egg yolk jellyfish near the Kamchatka Peninsula in eastern Russia. These jellies turn pale yellow with age. And while a bit stingy, the tentacles are sticky too, giving the species two ways to catch prey.
King Ragworm: This North Atlantic and Arctic resident is the seabed’s favorite snack, which is why it lives in crevices and catches prey by poking its jaws up to a quarter of its body length.
Colony of salps, a type of sea squirt, living next to each other in a spiral. These barrel-shaped filter feeders, when they are young, have a protective rod that runs the entire length of their nerve cord, making them and other starfish our closest invertebrate relatives.
Salp spiral from above: the creatures combine to form colonies that can be up to 8 meters long. Each member filters so much water that, depending on the number of salps, their droppings could shift the ocean’s carbon cycle.
Sea butterfly in the Sea of Japan: The maximum wingspan of these free-swimming molluscs is only one centimeter. But Semenov saw the White Sea go almost black when thousands of sea butterflies and their dark shells filled the water.
Crystal Jelly glows in the dark thanks to its green fluorescent protein. The researchers who identified and isolated the protein and developed its use as a fluorescence tracking device in other biological systems, which won a Nobel Prize for their work.