Sponges Cnidarians Ctenophores Parazoa and Radiata Sponges Cnidarians Ctenophores

Phylum Porifera: The Sponges

General Information Mainly marine organisms; evolved from choanoflagellates May have algae or bacteria that give them color Larva are flagellated, adults considered sessile Many disease-fighting compounds holdfast

Tube Sponges Encrusting Sponges

Characteristics Can reproduce sexually or asexually Gas exchange and excretion - diffusion at individual cells Supported by skeletal fibers: spicules or spongin Simple animals made of few specialized cells; NO tissues Asymmetrical Body with ostia Most are filter feeders / suspension feeders 1 family is carnivorous

Anatomy of a Sponge: Osculum Spongocoel Choanocyte Amoebocyte Mesohyl

Suspension Feeding & Gas Exchange

Sponge Reproduction: Asexual reproduction Buds or gemmules Sexually – most sponges are hermaphrodites Cells become egg/sperm Sperm released into water Fertilization occurs in mesohyl (egg) Zygote becomes flagellated larva that leaves in flow of water

Phylum Cnidaria Jellyfish Box jelly Sea anemone Coral

Main Characteristics Diploblastic, radial symmetry Cnidocytes with nematocysts concentrated in tentacles Gastrovascular cavity with 1 opening 2 layers separated by mesoglea Gas exchange and excretion occur by diffusion

Discharging of Nematocysts

Structure cont… Nerve nets Contractile cells Connect sensory cells to contractile cells Sense organs around edge of body Ex. photoreceptors Contractile cells Not true muscles Act as hydrostatic skeleton

Cnidarians come in 2 forms: Medusa – tentacles down Polyp – tentacles up Many alternate between medusa and polyp during life cycle

4 Classes of Cnidaria Hydrozoa Scyphozoa Cuboza Anthozoa

Cnidarians are Carnivores Feed on fish, larva, comb jellies, other zooplankton Sting prey with their tentacles Mouth  gastrovascular cavity  mouth Jellyfish.asf

A word about corals: Many have symbiotic zooxanthellae Environmental issue: Coral Bleaching

Portuguese Man-of-War Interesting Facts… Portuguese Man-of-War Colonial Has sail-like float Tentacles can grow up to 165 feet and are nearly invisible

More interesting facts… Box Jellies More toxic than Man-of-War Stings can lead to heart failure within minutes Tentacles may reach 15 feet

CTENOPHORA: THE COMB JELLIES Diploblastic??; Biradial Symmetry Swim with 8 rows of ciliary combs Have 2 long tentacles with sticky cells Colloblasts Eat large amounts of fish larva & plankton Mouth + 2 anal pores Introduced/Invasive species (Black Sea)