Range: Cosmopolitan Habitat: Open ocean, deep ocean, coastal areas, and more Size: 0.06 inches - 3 feet (1.5mm-91cm) long Diet: Jellyfish, copepods, fish and mollusc larvae, and other comb jellies Threats: Sea nettles and fish Life span: Several months to several years

Transcript:

Today on Animal Fact Files we’re talking about comb jellies. Though these blobby little sea creatures might be mistaken for jellyfish, they aren’t. Jellyfish is the common name for the medusa stage of Cnidarians, a phylum of animals with stinging cells. Comb jellies, on the other hand, don’t have these stinging cells - well, at least not normally, we’ll come back to this.

Comb jellies are currently classified in their own phylum: Ctenophora or Cteenophora. There are approximately 150 living species of these jellyfish-like animals and they get their common name from the hairlike structures, called cilia, around their bodies which they use for locomotion. Comb jellies have up to eight rows of cilia and these rows are called “comb rows” hence the common name. Comb jellies move these hair-like structures in a wave pattern in order to swim. They can even swim backwards! Not all comb jellies have these structures, though.

Comb jellies may also be known as sea gooseberries and sea walnuts likely in reference to their spherical appearance, but not all species look this way. There are approximately five main groups of comb jellies: those with round bodies and branched, retractable tentacles, those with compressed lobes extending from their bodies and shorter tentacles, those with ribbonlike bodies, those who look like nudibranchs, and those that are cone shaped and don’t have tentacles! It’s amazing how much variety can exist in a relatively small group of animals!

Comb jellies are pelagic meaning they live in the open ocean. They’re found throughout the world’s oceans. They are most abundant in warmer waters, but they’re even adapted to surviving in polar regions. It’s thought that some species that are native only to certain areas have been introduced outside of these areas by hitching rides in the ballasts of ships. Comb jellies may be found from the surface of the water column to more than 1.8 miles (3000m) below the waves - though they’re most often seen in warm water areas from spring to fall when they’re abundant in estuaries and coastal settings.

Most comb jelly species are hermaphroditic meaning they have both male and female gametes. When they come together to breed, each individual will release gametes into the water column and the eggs will be fertilized externally. There are however, exceptions to just about all of this. For one, some comb jellies are benthic meaning they live on the floor of the ocean. Here some species creep along the bottom and others are sessile, meaning they don’t move from the spot to which they’re anchored. There are also some species who are distinctly either male or female. And some species brood their eggs internally! So there’s still a lot of diversity. These animals can even range vastly in some with some species reaching only a few millimeters in length and others reaching more than three feet (91cm) in length with their long trailing tentacles.

Now, comb jellies do absolutely resemble jellyfish, but while holding a jellyfish could be quite a painful experience, holding a comb jelly would be quite harmless. At least to whoever is holding the comb jelly, the comb jelly itself might… well… disintegrate. These animals are extremely fragile and easily break apart when scientists try to collect them for study!

Predators to comb jellies include jellyfish like sea nettles and fish while the comb jellies themselves eat jellyfish, copepods, fish and mollusc larvae, and other comb jellies. Some comb jellies use their tentacles to capture prey. They have cells that release when touched that are kind of sticky like and hold the prey in place. There are some comb jellies who eat cnidarians with stinging cells and then utilize those stinging cells in their own bodies, this is similar to the sea dragon we’ve discussed previously. There are also comb jellies without tentacles who actively hunt their prey by swimming with their wide mouths open ready to catch a meal. Most comb jellies are transparent, but some come in colorful arrangements. Some comb jellies are also able to produce their own light.

For more facts on comb jellies check out the links in the description. Thank you to Ahmet and Night Fury for today’s request! Give a thumbs up if you learned something new today, and thank you for watching Animal Fact Files.