Marine Invertebrates Who are the Invertebrates Any animal

Marine Invertebrates

Who are the Invertebrates? § Any animal lacking a backbone § Lamarck (1809) § 98% of all animal species § Diversity rules in all aspects of their life § feeding (filter, predator, parasitic…) § morphology (stars, threads, torpedoes…) § reproduction(sexual, asexual) § habitats (benthic, pelagic, intertidal, open ocean)

§ Why study Invertebrates? § Ecological importance § Economic importance § Medical importance § Learning Strategy: § From simplest to most complex in terms of body organization. § Major taxa only § Unique (defining) features of each taxa

Phylum Porifera (The sponges) § Latin “Pore-bearers” § Body plan simple: § Multicellular, but without tissues § encrusting, globular, vaselike… Fig. 8 -5

§ Sessile lifestyle § Filter feeding forced water flow through flagellated channels § two cell layers § choanocytes = flagellated cells § pinacocytes = outer covering § § § spicules of Si. O 3 or Ca. CO 3 give support ostia = incurrent pores osculum = excurrent pore Fig. 8 -2

Phylum Cnidaria § Greek “stinging thread” § Body plan (Fig. 8 -7 b) § tissue level of construction (2 layers with mesoglea between) § 2 alternate body plans: § § polyp = sessile (anemone, corals) medusa = free-floating (jellyfish) § Many species possess both body plans in their life cycle (Fig. 8 -17, 8 -18) § Many species are colonial (polyp or medusa) (Fig. 8 -10 b, 8 -17)

§ Regardless of body plan type, all have: § radial symmetry § gastrovascular cavity with one opening § tentacles surrounding mouth § § batteries of stinging cells (cnidocytes) each cnidocyte contains a nematocyst § § barbed sticky toxic nematocysts discarged explosively for defense or prey capture Fig. 8 -8

Class Hydrozoa § Greek “water animals” § Ex. Physalia § Float using gas (N) filled pneumatophore § colonial organism with polyp members dangling beneath medusa § § § reproduction digestion offense/defense Fig. 8 -9 a, b

Class Anthozoa § Greek “flower animals” § Ex. Hard corals § polypoid body plan § colonial organization Fig. 8 -15 § secrete hard “cup” of Ca. CO 3 § layers of calcium carbonate build up to form reefs § endosymbiotic algae provide nutrients § Healthy reefs - clear, clean, shallow water

Class Scyphozoa § Greek “cup animals” § Ex. Moon jelly Aurelia § almost exclusively medusa form § solitary § predatory Fig. 8 -13

Phylum Ctenophora § Greek “comb bearer” (Fig. 8 -20, 8 A p. 206) § Very similar to Cnidarians § no nematocysts (“glue” cells instead) § rows of fused cilia called combs or “ctenes” for locomotion

Marine Worms § Since they belong to 13 different phyla, many differences exist between these organisms. § Shared characteristics: § worm-like (vermiform) § bilateral symmetry with cephalization (Fig. 8 -21) § efficient swimming, burrowing, tube-dwelling, and parasitic lifestyles

Phylum Annelida § Latin: annulus or “ring” § Most common group of marine worms § Body - segments (metamerism) with repeating body parts. § Possess tissues / organ systems (nervous, digestive, reproductive, excretory) and extensive musculature. § Fig. 9 -21

§ Burrowing lifestyle: § ex. Arenicola § lives in a L-shaped burrow in intertidal mud and sand § ingest sand/food at bottom of burrow and defecate undigestible parts at surface Fig. 9 -25 a

§ Tube-dwelling lifestyle § Ex. Feather dusters § secrete tubes to inhabit. § extend tentacles to collect particles (suspension feeders). § Retract tentacles into tube for protection Fig. 9 -22 b

§ Tube-dwelling lifestyle § Ex. Chaetopterus § secrete parchment-like tube to inhabit. § Two tube openings stick up out of mud § Pull water into tube, pass over mucus-covered “collectors” (suspension feeders). Fig. 9 -24

§ Free-living lifestyle § Ex. Fireworms § swim (although not particularly speedy) often using modified flaps of skin called parapodia. § Usually deposit feeders § Predatory species often use § § jaws (annelids) (Fig. 9 -23) special harpoon devices (nemerteans or ribbon worms) (Fig. 8 -23)

§ Parasitic lifestyle § ex. Nematodes, tapeworms and flukes § complex life cycles often including multiple hosts § definitive hosts usually vertebrate (in muscles, digestive tract, nasal and bronchial areas) Fig. 2 -16 c

Phylum Mollusca § Latin “soft” § Second largest animal phylum (after arthropods) § Extreme variation in size and shape

§ Shared characteristics: (Fig. 9 -2) § visceral mass containing organ systems § § § heart in pericardial cavity ganglia and nerve cords usually separate sexes (dioecious) § Mantle = secretes shell § foot = modified for movement and food acquisition § radula = tongue-like structure with teeth for scraping food (Fig. 9 -3)

Radula movie

Class Gastropoda (Fig. 9 -7) Greek “stomach foot” ex. Snails, conchs, limpets, nudibranchs single, coiled shell when present may graze using radula to scrape diatoms and algae, set mucus nets, or be predaceous. (Fig. 9 -8) § Trochophore and veliger larvae swim to allow dispersal (adults heavy, slow) Fig. 9 -10 § § § Sex change species: Crepidula fornicate (Fig. 9 -11)

Swimming

Class Bivalvia § § § (Fig. 9 -12) Latin “two shells” ex. Clams, oysters, scallops no radula, collect debris on leaf-like gills = ctenidia (in mantle cavity) and stuff into mouth. § bacteria and viruses (from sewage), and pollutants, concentrated in visceral mass § significant health risk to humans if poorly cooked prior to consumption.

Locomotion

§ § Class Cephalopoda (Fig. 9 -15) Greek “head foot” ex. Squid, octopus, nautilus shell variable (reduced, absent, present) most highly cephalized of all marine invertebrates § § § eyes highly developed rapid swimmers (some) by jet propulsion multiple muscular arms with suckers all predaceous carnivores able to learn and problem-solve

Squid locomotion smart cephalopods

Class Polyphacophora § Greek “many plate-bearer” § ex. chitons § shells of 8 overlapping plates § grazers using radula (Fig. 9 -5)