Animal Phyla/Ctenophora

Mertensia, a Ctenophore.

• Ctenophora
• Name Meaning: Comb bearer
• English Common Name: Comb jellies, Ctenophores
• Major distinguishing characteristics: Eight "comb rows" of fused cilia
• Approximate number of species described: about 100 modern species

Natural History

All species are marine and almost all are free-swimming. They are found around the world, and grow up to 2 meters (6 feet) in length.

Comb-jellies are difficult to study because most species are extremely soft-bodied and don't survive capture intact. A few coastal species are a bit tougher, and are regularly displayed in aquaria. Most of what we know about them comes from these species.

All adult ctenophores are predators. The juveniles of two species are parasites, otherwise they too are predators. Some are bioluminescent.

Taxonomy

The Phylum Ctenophora is divided into two living orders:

• Order Tentaculata (ctenophores with cilia)
• Order Nuda (ctenophores without cilia)

Anatomy

Ctenophora are the largest animals to move by the use of cilia. The cilia are present in lines, called combs. A few deep-sea ctenophorans lack combs.

Like cnidarians, their bodies consist mostly of mesoglea, a non-living substance. Unlike the cnidarians, their body wall contains two layers of cells instead of one. Their internal anatomy consists of a mouth, pharynx, stomach, and an internal set of canals.

The Fossil Record

Having a soft body, the fossil record of the Ctenophora is spotty and limited. The earliest known is 520 million years old.

They are present in the Burgess Shale.

Quiz

• Ctenophora Quiz

References and Further Reading

• Ctenophora at Wikipedia
• Ctenophora at the Encyclopedia of Life
• Ctenophora at the Tree of Life