BIOL 111 Study Guide - Final Guide: Sternum, Hydrostatic Skeleton, Planula

• School: McGill University
• Department: Biology (Sci)
• Course: BIOL 111
• Professor: Suzanne Gray

Document Summary

Medusa stage, yet spends most of its time clinging to sea-grasses. Contains a thick mesoglea (acts as a hydrostatic skeleton and provides. Can be poisonous due to toxins in the nematocysts. Sexual reproduction: sperm and egg are released into the water. Egg produces a small, larvae called a planula. Planula attaches to an object and begins its life as small polyp. Soon develops into a medusa form, when ready. Bell: dome-shaped structure that contains the epidermis, gastrodermis and mesoglea. Tentacles: arms that hang out of the bell, used for capturing prey and attaching to objects. Tentacular bulbs: dark swellings at the base of each tentacle, contain interstitial cells that develop into cnidocytes when old ones get discharged. Adhesive pads: at the tip of each tentacles, used to attach to objects. Cnidocytes: stinging cells that occur in spiral swellings (batteries) along the length of the tentacles. Velum: shelf underneath the bell, assists in contractions up, downwards is passive movement = sinking.