#ctenophore

Determining which lineage of animals is most distantly related to humans is among the most important and heated disputes in evolutionary biology.

Using an integrative phylogenomic approach, new research in Science reveals unprecedented phylogenomic support for sponges as the sister lineage to all other animals.

Solving this puzzle is key to revealing the biology of the ancestors of all animals, including how they transitioned from single-celled to multicellular organisms and radiated to the dazzling diversity seen today. Scientists typically decipher the evolutionary relationships between species with phylogenomics, which uses computer models of how sequences evolve to analyze large datasets of genes. Steenwyk and King (1) unexpectedly refresh this phylogenomic inference approach by using only genes with strong and consistent phylogenetic signal for either of two major competing hypotheses. This strategy reveals unprecedented phylogenomic support for sponges (phylum Porifera), filterfeeders lacking organized tissues, as the sister lineage to all other animals and may also have the potential to resolve other difficult phylogenetic problems.

Submitted for classification by anonymous.

UFOs? A music festival viewed from space? Some sort of rare gem earrings? No, these are Mnemiopsis leidyi, aka comb jellies!

Comb jellies are ctenophores, and we’re highlighting them today in honor of Ctenophore Day. Ctenophores are often referred to as jellies due to their appearance, but they are actually a type of gelatinous animal in their own phylum. There are at least 100 species in this phylum, Ctenophora (Greek for combbearers and pronounced teen-o-for-uh).

While they have similarly translucent bodies, live in the same waters, and eat the same kinds of food, combs and other ctenophores are not true jellies due to the lack of stinging cells. Instead, ctenophores have sticky cells called colloblasts that do not sting, and eight rows of cilia, or combs, that propel them through the water, producing a flickering, rainbow-like appearance with their movements. 🌈

Scientists once categorized sea jellies and ctenophores in the same phylum, but the differences between these groups have now been well characterized. Both jellies and ctenophores are now on display at the Aquarium!

You can learn more about comb jellies in our Online Learning Center.