#combjellies

Looking at delicate deep-sea drifters reveals adaptations to life under pressure.

Deep-sea animals live under crushing amounts of pressure generated by the immense weight of the water above. Comb jellies are a diverse group of gelatinous animals found across a range of marine habitats, from the ocean’s sunlit surface to the abyssal seafloor. A new study published in Science today by scientists at the University of California, San Diego with an interdisciplinary team of researchers, including MBARI marine biologists, has revealed how comb jellies manage to thrive under pressure.

For comb jellies, an adaptation in their cellular membranes is key to surviving high pressure. Greasy molecules called lipids that make up membranes have a different shape in deep-sea species than in shallow-water ones. The cone shape of these molecules helps keep the cellular membranes of deep-sea comb jellies dynamic under pressure. These molecules are also abundant in our own nerve cells and their loss is linked to conditions like Alzheimer’s. Studying deep-sea comb jellies could one day help us find ways to restore membrane function in human brains.

Ctenophores are more commonly known as Comb jellies, are marine invertebrates and resemble Cnidarians with a few notable similarities. Such as, lacking true organs, being mostly water, hollow gut, carnivorous behavior, tentacles, and are both diploblastic (having a body w/ only two embryonic layers). Many differences too though, like all cnidarians have stinging cells in their tentacles called nematocysts or cnidocytes (even if their stinging power isn’t always strong) but ctenophora have tentacles lined with sticky cells (colloblasts) so that they can catch prey. They also have different body shapes, Cnidarians that we consider jellyfish are radially symmetrical but Ctenophora are biradially symmetrical.

Bloodybelly Combjelly (Lampocteis cruentiventer).

The cilia of Combjellies are arranged in eight rows. As the cilia beat, they diffract light, resulting in the rippling rainbow effect.

The phylum Ctenophora is a relatively small phylum of about 150 valid species, or even less depending on who you ask. They are actually not related to Cnidarians or Jellyfish even though both Ctenophores and Jellyfish are loosely referred to as jellies. Defining features include biradial symmetry, sticky cells (colloblasts),an aboral sense organ, rows of cillial band, and instead of a regular nervous system they have a non centralized net (Much like Cnidarians!!!).   

There’s 3 main types of Ctenophores: 

Cypiddids which have round bodies, sometimes spherical or oval with branched tentacles that they can bring back into pouches near their mouth.

Beroids who have no tentacles, are sack shaped and have a huge mouth that can be shut extremely tight. They eat by engulfing their prey 

Lobates which are larger than Cypiddids and are classified by the flat lobes below their mouth and their short tentacles.