Sponges, Cnidarians, Comb Jellies, and Marine Worms

What are Animals? Multicellular Eukaryotic (lack cell walls) Cannot produce their own food (heterotrophs) Can move (exception: adult sponges)

Vertebrates: have a backbone (vertebral column) Invertebrates: do not have a backbone (no vertebral column) –Majority of marine animals

Sponges (Phylum Porifera) Simple Asymmetric Sessile (cannot move)

Structure and Function Full of tiny holes/pores called ostia –Water circulation (nutrients and oxygen) –Carries away wastes Lack tissues and organs Size is limited by ability to circulate water through its body

3 possible body plans –Asconoid (simplest)-tubular and small –Syconoid (body-wall folding)-internal pockets –Leuconoid (highest degree of folding)

Nutrition and digestion: –Suspension feeders (filter feeders)  Get food from water Reproduction –Sexual Hermaphrodites –Asexual Budding  pinching off to form new organism Fragmentation  pieces form new organism

Ecological roles –Can produce chemicals that can kill coral or inhibit growth –Can provide camouflage and protection for animals –Can produce chemicals that prevent organisms from settling on their surface or to deter grazing –Hosts to other organisms –Recycles calcium to seawater

Cnidarians (Phylum Coelenterata) Ex: jellyfish, hydra, coral, and sea anemones Radial symmetry

Structure and Function: 2 different body plans –Polyp: benthic form Cylindrical body with an opening a 1 end (mouth) Surrounded by tentacles –Medusa: free-floating stage –Gelatinous material between layers of body called mesoglea

Stinging cells (cnidocytes) –Common on tentacles and outer body wall –Can also release toxins

Nutrition and digestion –Digests prey in gastrovascular cavity –Filter-feeders –Can be carnivores Paralyze prey with toxins Reproduction –Asexual  polyp stage –Sexual  medusa stage

Ecological relationships –Predators that feed on a variety of prey –Provide habitats for organisms (ex: corals) –Host symbionts that aid in nutrition and help them grow

Ctenophores (Comb Jellies) Structure and Function: –Transparent bodies –Lack stinging cells –Planktonic –Eight rows of comb plates used for locomotion Made of large cilia –Weak swimmers –Found mostly in surface water –Radial symmetry –Luminescent at night

Nutrition and Digestion –Carnivorous Reproduction –Hermaphrodites –Shed eggs and sperm directly into the water column –Few species can brood eggs in their bodies

Marine Worms Most are benthic Structure: Elongated bodies Lack external hard covering Gain support for body from fluid in body compartments –Hydrostatic skeleton

Flatworms Flattened bodies Structure: Head and posterior end Free-living or parasitic Bilateral symmetry Ex: flukes and tapeworms

Nutrition and digestion: –Chemical-detecting organs called chemoreceptors –Carnivorous –Can subdue prey by entangling it in mucus and suffocating it –Can stab prey –Digestion in gastrovascular cavity Reproduction: –Asexually  regeneration –Sexually Hermaphrodites Can fertilize each other Internal fertilization No larval stage

Nematodes Roundworms –12,000 species Structure: Round, slender body –Elongated –Tapered at both ends Nutrition/Digestion: –Scavengers, parasites –Carnivorous, free-living Reproduction: –Most are hermaphroditic –Some can have separate sexes

Annelids Segmented Structure and Function: Body wall has muscle Skin has setae (small bristles used for locomotion, digging, anchorage, and protection)

Feeding and digestion: –Can have jaws or teeth –Active predators –Chemoreceptors monitor water currents –Filter-feeders Reproduction –Asexual Budding Regeneration Fragmentation –Sexual Separate sexes Gametes shed into body cavity where they mature

Ecological roles: –Burrowing aids in nutrient cycling –Burrows provide habitats for other species –Feed on microorganisms and detritus

Examples of Annelids polychaetesechiuranspogonophorans