Chapter 12

Topics: Sponge, Animal, Phylum Pages: 2 (616 words) Published: December 1, 2014
1. The term “metazoan” is a synonym with “multicellular animal.” Are there any single celled animals? How are single-celled eukaryotes classified? 2. Give eight characteristics of sponges. Multicellular animals, body had pores, canals, and chambers, all sponges are mostly marine or totally aquatic, they exhibit radial symmetry or no symmetry, all adults are sessile and attached to the substratum no organs or true tissue are present, asexual reproduction occurs by buds or germmules, outer surface consist of flat pinacocytes. 3. Briefly describe asconoid, synconoid, and leuconoid body tpes in sponges. Asconoid they have the simplest organization. Water is drawn into the sponge through microscopic dermal pores by beating of flagella on choanocytes. Synconoid have a tubular body and single osculum and the body wall lining the Spongocel is thicker and more complex than asconoid. Leuconoid it is the most complex in organization. 4. What sponge body type is most efficient and makes possible the largest body size? Leuconoid type of canal system. 5. Define the following ostia, osculum, sponogocoel, apopyles, prosopyles, spicules. Otisia- the pores through which water enters the sponge body. Osculum- the large opening through which water exits out. Sponogocoel- it is the internal cavity lined by choancytes. Apopyles- the pores through which water is forced into the spongocoel and out of the body. Propsopyles- The pores which allows water to enter into the radial canals which are lined with choanocytes for food ingestion. Spicules- small needle like structure made of silicate or calcium carbonate, used for supporting the soft tissue in sponges. 6. Define the following pinacocytes, choanocytes, archaeocytes, sclerocytes, spongocytes, collncytes. Pinacocytes- they are thin flat, epithelial like cells that cover the exterior surface and some interior surfaces of a sponge. Choanocytes- they are ovoid cells with one end embedded in mesohyl and other end exposed which bears a...
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