Ch 33 – Sponges, Cnidarians, and Ctenophores Vocabulary Review Ch 33 – Sponges, Cnidarians, and Ctenophores

An aquatic invertebrate of the phylum Porifera that attaches to stones or plants and that has a porous structure and a tough, elastic skeleton Sponge

Describes an organism that remains attached to a surface for its entire life and does not move Sessile

Any of the flagellate cells that line the cavities of a sponge Choanocyte

One of the small openings in a sponge’s body through which water enters Ostium

An opening in a sponge’s body through which water exits Osculum

A fibrous protein that contains sulfur and composes the fibers of the skeleton of some sponges Spongin

A needle of silica or calcium carbonate in the skeleton of some sponges Spicule

In an aquatic animal, a method of feeding in which the animal traps organic material that is floating in the surrounding water Filter feeding

Within the body wall of a sponge, a specialized cell that crawls about and delivers nutrients from the choanocytes to the rest of the body cells Amoebocyte

An asexual reproductive structure produced by some freshwater sponges Gemmule

The regrowth of missing tissues or organs Regeneration

An organism that has both male and female reproductive organs Hermaphrodite

A free-swimming, jellyfish-like and often umbrella-shaped sexual stage in the life cycle of a cnidarian; also a jellyfish or a hydra Medusa

A form of a cnidarian that has a cylindrical, hollow body and that is usually attached to a rock or to another object Polyp

The outer surface layer of cells of a plant or animal Epidermis

In cnidarians, the layer of cells surrounding the digestive tract Gastrodermis

In cnidarians, the jellylike material located between the ectoderm and the endoderm Mesoglea

Gastrovascular cavity A cavity that serves both digestive and circulatory purposes in some cnidarians Gastrovascular cavity

A flexible appendage with which an animal feeds itself, grasps objects, or feels its environment Tentacle

A stinging cell of a cnidarian Cnidocyte

In cnidarians, a stinging cell that is used to inject a toxin into prey Nematocyst

In cnidarians, a network of nerve cells that lacks a central control; impulses pass in any or all directions to produce a generalized response Nerve net

The free-swimming, ciliated larva of a cnidarian Planula

A limestone ridge found in tropical climates and composed of coral fragments that are deposited around organic remains Coral reef

A cell that is found on the tentacles of a ctenophore and that secretes a sticky substance Colloblast

In ctenophores, a sensory structure that enables the animal to sense its orientation in water; in annelids, a ciliated plate located at the back of the larva Apical organ

The production of light by means of a chemical reaction in an organism Bioluminescence