Sea gooseberry, comb jellies
Pleurobrachia bachei average 1 cm, up to about 2 cm.
Pleurobrachia are found all over the world.
Pleurobrachia bachei lives in the epipelagic zone of marine environments.
The body structure of Pleurobrachia bachei is: spherical, biradial symmetrical, with eight rows of ciliated bands (appearing iridescent), two tentacles (with tentilla hanging down from tentacles), and a branched digestive system. The three dermal layers are: epidermis, mesoglea, and gastrodermis. They lack cnidae and are considered monomorphic with one stage (the "medusa") lacking alternation of generations.
Pleurobrachia are pelagic-they can maneuver the body with cilia aboral end first contain statocysts (aka: apical sense organ) for coordination and orientation. Eating consists of dragging tentacles across the oral cavity.
Pleurobrachia bachei prey upon copepods.
The main predators of Pleurobrachia bachei are Aurelia aurita and other pelagic jellies.
Because Pleurobrachia bachei are hermaphroditic (both male and female reproductive organs) they shed their gametes through the mouth into the water where fertilization can take place.
It is believed that ctenophores originated from hydrozoans, through the medusa stage. There are studies going on now to try to link them to flat worms and also to cnidarians. Even within the ctenaphore phylum there is debate, i.e. the origins of the Tentaculata. As with most phylogenetic history, it is always being challenged and revised.
Linnaeus, a doctor and naturalist, was the first to classify the ctenophores in his group Zoophyta, in 1671. Cuvier then placed them in a sub-category with the medusa and anemones. Eschscholtz followed in the early nineteenth century, to start a classification system of pelagic medusa, which he used to placed the ctenophores in Ctenophorae and Discophorae for the other cnidarian medusae.
Brusca, R., Brusca,G. (1990)Invertebrates.Sinauer Associates, Sunderland, MA Pg.263-277
Laveract,M., Dando, J.(1987) Lecture Notes on Invertebrate Zoology. Blackwell Scientific Publications, Oxford. Pg.38-41
Last updated Monday, August 21, 2006, by Lisa Ferrier