Invertebrates I: Porifera, Cnidaria,

Tree of Life

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

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

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

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

Fig. 7.5 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) III. Phylum Cnidaria

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

No true organs Tube/sac with single opening (mouth) Mouth opens to gut Mouth opens to gut Tentacles capture food Tentacles capture food CNIDOCYSTS (stinging cells, NOTE NAME) CNIDOCYSTS (stinging cells, NOTE NAME) Defense Defense Prey capture Prey capture Contain NEMATOCYSTS =thread bag (stinging capsule) Contain NEMATOCYSTS =thread bag (stinging capsule) Simple nervous system Simple nervous system Trap food using mucus secreted at mouth and tentacles Some with symbiotic zooxanthellae, provides host with nutrients, O 2, use up CO 2 III. Phylum Cnidaria-feeding

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 III. Phylum Cnidaria

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

Cyanea capillata

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

Branching CoralsDoming Corals

Soft Corals Sea Pen Sea Pansy

Gorgonians (Sea Whips)

Gorgonians (Sea Fans)

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

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

Beroe Pleurobrachia