Invertebrates Facts

  • Invertebrates are multi-cellular and all the cells have different responsibilities to keep the animal alive.
  • Invertebrates have no backbone or bony skeleton or cells wall like all other animals.
  • Invertebrates like echinoderms do not have heads.
  • There are millions of invertebrates living in our house in the name of dust mites which are hardly visible to human eyes.
  • Invertebrates under a process called metamorphosis through which they change form as they grow.



The phylum Ctenophora is one of the species which live mainly in the marine waters worldwide. The main notorious thing in this species is that its combs. It has group of cilia that are useful to them for swimming.

This is the largest animal species that uses cilia for swimming. The size of this species ranges from few millimeters to 1.5 meters. Most of the features of Ctenophora can resemble the species Cnidarians. The body of the Cnidarians is having mass of jelly with one cell deep. Whereas the body of Ctenophora also having mass of jelly with two cell deep.

One layer of cells covering the outside of the body and the second layer of cells are lining the internal cavity. The next similarity is that the Ctenophores having a decentralized nerve net instead of brain. Some researchers argue that both Ctenophores and Cnidarians are under the same phylum. But the recent researches have shown that they are not under the same phylum.

All the Ctenophores are predators; they can take their prey from microscopic larvae, rotifers and small crustaceans. There are about 100 - 150 valid species found but some more species are not described and named.

During the summer season the Ctenophores are found abundantly in the coastal locations. It is difficult to find it in the other places. Most of the species of Ctenophores can swim, whereas one group can creeps in the bottom of the sea.

Most species live on other animals like echinoderms, sponges, and benthic cnidarians. Ctenophores are also called as comb jellies, sea gooseberries, sea walnuts or Venus's girdles. Ctenophora are hermaphrodites, that is both sperm and eggs are produced in the single animal.

If both the egg and the sperm produced at the same time then the resulting species is also a hermaphrodite whereas the egg and the sperm mature at different times then the resulting species is a sequential hermaphrodite.

Though the male and female reproductive organs present in the same animal, asexual reproduction can also take place in very few species. In some cases the eggs and the sperms are unfortunately shed into the water and the fertilization takes place there and forms the larvae. These larvae can swim independently in the water and grow into a new comb jelly

Some of the species of Ctenophora are:

  • Coastal ctenophores
  • Oceanic ctenophores
  • Benthic (bottom-living) ctenophores
  • Ctenophore light-scattering and bio luminescence

Features of Ctenophora:

  • Radially or biradial Symmetrical
  • Body multicellular, few tissues, some organs and organelles
  • Body contains an internal cavity and a mouth and anal pores
  • Swims with the help of cilia (the combs)
  • Reproduction mostly sexual as hermaphrodites, occasionally asexual
  • Having well developed subepidermal nerve net
  • Lives in marine environments
  • All are carnivorous

Recent Videos

Snowball(TM) Rocks The World Science Festival
Very Smart Mathematical Dog

From the Gallery