Question | Answer |
A hypothesis formulated to explain the origin of multicellularity from protis ancestors. Animals may have been derived when protists associated and cells became specialized and interdependen. | Colonial Hypothesis |
The idea that multicellular organisms could have arisen by the formation of plasma membranes within a large, multinucleaste protists. | Syncytial Hypothesis |
Thin, flat cell covering the outher surface, and some of the inner surface of poriferans. | Pinacocytes |
Tubular cells in sponge body wall that create a water channel to an interior chamber. | Porocytes |
A jellylike layer between the outer and inner layers of a sponge. Contains wandering amoeboid cells. | Mesohyl |
Amoeboid cells within the mesohyl of a sponge. Mesenchyme cells are specialized for reproduction, secreting skeletal elements, transporting food, storing food, and forming contractile rings around openings in the sponge wall. | Mesenchyme cells |
Cells of sponges that create water currents and filter food. | Choanocytes |
Skeletal elements that some mesenchyme cells of a sponge body wall secrete. May be made of calcum carbonate or silica. | Spicules |
A fibrous protein that makes up the supportive framework of some sponges. | Spongin |
The simplest of the three sponge body forms. These sponges are vaselike, with choanocytes directly lining the spongocoel. | Ascon |
A sponge body form characterized by choanocytes lining radial canals. | Sycon |
The sponge body form that has an extensively branched canal system. The canals lead to chambers line by choanocytes. | Leucon |
The immature stage of the sponge in which the adults and immatures are different in body form and habitat. | Larva |
Resitstant, overwintering capsule formed by freshwater, and some marine, sponges that contains masses of mesenchyme cells. Amoeboid mesenchyme cells are released and organize into a sponge. | Gemmules |
A sheet of cells covering the surface of an animal's body. | Epidermis |
The endodermally derived lining of the gastrovascular cavity of Cnidaria. | Gastrodermis |
A gel-like matrixs between the epidermis and gastrodermis of cnidarians. | Mesoglea |
An organelle charactristic of the cnidaria that is used in defense, food gathering, and attachment. | Cnida |
The cells that produce and discharge the cnidea in members of the phylum Cnidaria. | Cnidocytes |
A cnidarian cnida usually armed with spines or barbs and containing a venom that is injected into a prey's flesh. | Nematocysts |
Usually, the sexual stage in the life cycle of cnidarians. The jellyfish body form. | Medusa |
The attached, usually asexual, stage of cnidarian. | Polyp |
The use of body cavity fluids, confined by the body wall, to give support. | Hydrostatic Skeleton |
A ciliated free swimming larva of most cnidarians. This develops following sexual reproduction and metamorphoses into a polyp. | Planula |
A feeding polyp in a colonial hydrozoan. | Gastrozooid |
A polyp of a hydrozoan cnidarian that produces medusea. | Gonozooid |
A structure that hangs from the oral surface of a cnidarian medusa and surrounds the mouth. | Manubrium |
An organ of equilibrium and balance in many invertebrates. They usually consist of a fluid-filled cavity containing sensory hairs and a mineral mass called a statolith. | Statocyst |
A sensory structure at the margin of the scyphozoan medusa. It consists of a staocyst and a photoreceptor. | Rhopalium |
The polyp stage of a scyphozoan. | Scyphistoma |
Miniature medusa produced by asexual budding of a scyphistoma. They develop into sexually mature medusa. | Ephyrae |
The condition in a hermaphrodite in which male gonads mature before female gametes. Prevents self fertilization. | Protandry |
Rows of cilia that are the locomotor organs of ctenophorns. | Comb Rows |
Adhesive cells on ctenophoran tentacles for capturing prey. | Colloblasts |