BIOL113 L25
What are the characteristics of sponges?; Sessile with porous bodies, choanocytes, loose federations of cells, lack nerves or muscles, and capable of extensive regeneration.
How do sponges sense and react to changes in the environment?; Individual cells can sense and react to changes in the environment.
What is the function of the spongocoel in sponges?; Water is drawn through the pores into a central cavity, the spongocoel, and flows out through a larger opening, the osculum.
How do sponges feed?; Most sponges are suspension feeders, collecting food particles from water passing through food-trapping equipment.
What are the components of the body of a sponge?; The body of a sponge consists of two cell layers separated by a gelatinous region, the mesohyl, and wandering through the mesohyl are amoebocytes.
How do sponges reproduce?; Most sponges are hermaphrodites, with each individual producing both sperm and eggs. Gametes arise from choanocytes or amoebocytes, and zygotes develop into flagellated, swimming larvae that disperse from the parent.
What is the oldest eumetazoan clade?; The Radiata, animals with radial symmetry and diploblastic embryos.
What are the characteristics of cnidarians' body construction?; Radial symmetry, a gastrovascular cavity, and cnidocytes.
How many living species are there in the cnidarian group?; Over 10,000 living species, most of which are marine.
What are the two variations of the basic cnidarian body plan?; The sessile polyp and the floating medusa.
How do cylindrical polyps, such as hydras and sea anemones, capture prey?; They adhere to the substratum by the aboral end and extend their tentacles, waiting for prey.
What are the characteristics of medusas (jellies) in the cnidarian group?; They are flattened, mouth-down versions of polyps that move by drifting passively and by contacting their bell-shaped bodies.
How do cnidarians capture prey?; They use tentacles arranged in a ring around the mouth to capture prey and push the food into the gastrovascular chamber for digestion.
What are cnidae and what is their function?; Organelles that can inject poison into the prey, or stick to or entangle the target.
What is the role of the gastrovascular cavity in cnidarians?; It acts as a hydrostatic skeleton against which the contractile cells can work when the animal closes its mouth.
How are movements controlled in cnidarians?; By a noncentralized nerve net associated with simple sensory receptors that are distributed radially around the body.
How is the phylum Cnidaria divided?; Into four major classes: Hydrozoa, Scyphozoa, Cubozoa, and Anthozoa.
What is the life cycle of most hydrozoans?; They alternate polyp and medusa forms, as in the life cycle of Obelia.
What is the unusual characteristic of hydras among the class Hydrozoa?; They exist only in the polyp form.
How do hydras reproduce asexually?; By budding, the formation of outgrowths that pinch off from the parent to live independently.
What prevails in the life cycle of class Scyphozoa?; The medusa generally prevails in the life cycle of class Scyphozoa.
What is the characteristic of jellies that live in the open ocean?; They generally lack the sessile polyp.
What class do sea anemones and corals belong to?; Anthozoa.
How do coral animals live?; As solitary or colonial forms and secrete a hard external skeleton of calcium carbonate.
What do polyp generations build to form skeletons called?; Coral.
What do coral reefs provide habitat for in tropical seas?; A great diversity of invertebrates and fishes.
What is one suspect for the current damage to coral reefs in many parts of the world?; Global warming.
What class do box jellyfish belong to?; Cubozoa.
What is the life cycle of box jellyfish?; Includes a medusa and small polyp stage.
What makes box jellyfish more developed than Schyphozoa?; They have a more advanced nervous system and functioning eyes.
What makes flatworms acoelomates?; They lack a body cavity.
How many species of flatworms are there?; About 20,000 species.
What are some habitats where flatworms live?; Marine, freshwater, and damp terrestrial habitats.
What is the role of mesoderm in flatworms?; It contributes to more complex organs and organ systems and to true muscle tissue.
How do flatworms remove nitrogenous wastes?; By diffusion.
How do planarians move?; Using cilia on the ventral epidermis, gliding along a film of mucus they secrete.
What is the reproductive method of planarians?; They can reproduce asexually through regeneration and sexually through hermaphroditic cross-fertilization.