Invertebrates I: Porifera , Cnidaria ,

1. Invertebrates I:Porifera, Cnidaria,

2. Tree of Life

3. Invertebrates - Background • Kingdom Animalia • 97% of all animal species are invertebrates • Animals without a backbone • All major groups have marine representatives (some are exclusively marine) • (3-15 million species)

4. Phylum Porifera (Sponges) • Simplest multicellular animals • Most are marine (~9000 species) • Sessile (attached to substrate) • Diversity of shapes, sizes, colors, habitats • Found from low tide line to 3.5 miles deep

5. Shapes: Tiny cups, broad branches, tall vases, encrusting round masses

6. Phylum Cnidaria • Big steps from simple sponges to evolution of tissues • > 10,000 species • All are aquatic, mostly marine • Sea anemones • Corals • Jellies

7. III. Phylum Cnidaria Radial symmetry- similar parts of body are arranged and repeated around central axis. Look the same from all sides and have neither head or tail, front or back Oral surface (mouth) Aboral surface (opposite) Fig. 7.5

8. III. Phylum Cnidaria 2 basic forms • Polyp: anemone, tube with a mouth surrounded by tentacles, specialized in sedentary (sessile) life attached to substrate • Medusa: jellyfish, bell-shaped free-floating, swim by pulsating contractions

9. III. Phylum Cnidaria-feeding No true organs Tube/sac with single opening (mouth) Mouth opens to gut Tentacles capture food • CNIDOCYSTS (stinging cells, NOTE NAME) • Defense • Prey capture • Contain NEMATOCYSTS =thread bag (stinging capsule) • Simple nervous system Trap food using mucus secreted at mouth and tentacles Some with symbiotic zooxanthellae, provides host with nutrients, O2, use up CO2

10. III. Phylum Cnidaria 4 Classes of cnidarians Class Hydrozoa (includes hydras, hydroids, hydromedusae, chondrophorans, siphonophores, hydrocorallines) Feathery, bushy colonies of tiny polyps attach to pilings, shells, surfaces Alternate between polyp and medusa form

11. III. Phylum Cnidaria Class Scyphozoa-jellyfishes • All marine species, few hundred • Medusae large (dominant stage) • E.g. – Cyanea capillata (Lion’s Mane) • Bell > 2 m • Tentacles 60+ m • Swim by contracting bell rhythmically, pulsing contraction, at mercy of currents • Stings *, sometimes fatal Desmonema glaciale Aurelia aurita

12. Cyanea capillata

13. III. Phylum Cnidaria Class Anthozoa (most are) • Polyp (more complex than hydrozoan, scyphozoan • Sexes usually separate • Oviparous (egg-bearer) and viviparous (young bearing) • Passive suspension feeders • Solitary forms • Sea anemones • Colonial forms • Corals • Stony corals – branching and massive • - Some build reefs • Soft corals • Gorgonians • Sea pens • Sea pansies • (Drawings: Brain coral and Gorgonian specimen) Anthopleura xanthogrammica

14. Branching Corals Doming Corals

15. Sea Pen Soft Corals Sea Pansy

16. Gorgonians (Sea Whips)

17. Gorgonians (Sea Fans)

18. III. Phylum Cnidaria Class Cubozoa, “scyphozoa cubed” • Sea wasps, Box jellyfish • square bell-cuboidal swimming bell • 4 tentacles or bunches • Highly toxic

19. IV. Phylum Ctenophora (comb-bearing) Exclusively Marine (100 species) Aka comb jellies Resemble Cnidarians Most primitive Biradial symmetry (radial + bilateral symmetry) • 8 rows of ciliary combs (ctenes) • Equally spaced on body surface • Each row is a ridge, paddle of fused cilia • Beat aboral to oral, propels mouth forward • Organ system: Digestive system-mouth to pharynx to stomach • Predatory and Carnivorous • Lack nematocysts • Capture prey with sticky colloblasts • May occur in swarms • Heavy predators • (consume lots of fish larvae)

20. Pleurobrachia Beroe