Ch 26- Sponges and Cnidarians • What characteristics do all animals share? – Members of kingdom Animalia, multicellular, eukaryotic heterotrophs, lack cell walls • Invertebrates- animals that do not have a backbone – 95% of all animal species – Range in size from dust mites to giant squids • Vertebrates- animals that have a backbone – Fish, amphibians, reptiles, birds, mammals
Ch 26- Sponges and Cnidarians. What characteristics do all animals share? Members of kingdom Animalia , multicellular , eukaryotic heterotrophs , lack cell walls Invertebrates- animals that do not have a backbone 95% of all animal species Range in size from dust mites to giant squids - PowerPoint PPT Presentation
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Ch 26- Sponges and Cnidarians
• What characteristics do all animals share?– Members of kingdom Animalia, multicellular,
eukaryotic heterotrophs, lack cell walls• Invertebrates- animals that do not have a
backbone– 95% of all animal species– Range in size from dust mites to giant squids
• Vertebrates- animals that have a backbone– Fish, amphibians, reptiles, birds, mammals
• What essential functions do animals carry out?– Feeding, respiration, circulation, response,
movement, and reproduction• What are the important trends in animal
evolution?– High levels of cell specialization and internal body
organization in complex animals– Bilateral body symmetry– Front end or head with sense organs– Body cavity
Sponges• Why are sponges classified as animals?
– Multicellular, heterotrophic, no cell walls, contain a few specialized cells• Phylum Porifera • Are sessile and filter feeders• Body plan
– Asymmetrical, forms wall around large central cavity– Choanocytes- specialized cells that use flagella to move steady current of
water through sponge– Osculum- large hole at top of sponge– Spicule- spike shaped structrure made of chalklike calcium carbonate– Archaeocytes- specialized cells that move around within the walls of
sponge
• How do sponges carry out essential functions?– Movement of water throughout sponge
• Characteristics of sponges• No true tissues or organs– Food digested by collar cells and nutrients are passed to rest of body– Produce toxins – Feed on bacteria, protozoans, unicellular algae– May reproduce either sexually or asexually
• Internal fertilization• Gemmules- groups of archaeocytes surrounded by tough layer of spicules
• Play an important role in the primary productivity of coral reefs
Cnidarians
• What is a cnidarian?– Soft-bodied, carnivorous animals with stinging
tentacles arranged in circles around their mouths– Simplest animals to have body symmetry and
specialized tissues• Cnidocyte- stinging cells, located along