Animals without backbones We ll cover characteristics of major phyla and some to class level (KPCOFGS) We ll also cover some natural history Refer to your notes that I posted on-line! Invertebrates Levels of complexity change (become more complex) as we move up the evolutionary tree Ancient animals are no better or worse adapted than more complex animals. Its all about survival. Lophophorates Ctenophores here too Sponges: Porifera pore bearer No real symmetry, associations of loosely aggregated cells - very simple! Coanocytes (flagellated), collar cells, allow for food intake and O2. Osculum is excurrent pore (can have several), pore cells intake water Skeleton Spicules (CaCO3, or SiO2), or spongin (household sponges) Ecology: sessile, benthic, filter feeder. Encrusting and upright, and boring Most are hermaphrodites: eggs and sperm (broadcast). Fertilization is internal. Also have asexual reproduction: budding, re-aggregation Sponges are Suspension Feeders Choanocytes or Collar cells - flagellated food-trapping cells of a sponge that generate a current through the pores Water out through Osculum Water in through Pore Cells Water 1
Cnidaria Radial symmetry similar parts of the body are repeated around the center. No front or back, No head Oral surface (mouth side) aboral surface (opposite of mouth side) Two Body Forms Polyp -cylindrical and usually attached Corals, Anemones many colonial hydroids Medusa - umbrella-like swimming form upside-down polyp adapted for swimming Feeding Polyps on colonial hydroid Polyp Medusa Phylum Cnidaria Diverse forms: jellyfish, corals, anemones, sea fans etc. Stinging cells = nematocysts Gastrovascular cavity digestion and absorbtion of nutrients. Waste through mouth! Respiration occurs through diffusion. Hydrostatic (water) skeleton Ecology: sessile and benthic, as well as free swimming (planktonic). Filter feeders and predators. Some are colonial animals. (corals, sea fans, gorgonians, man-owar). Some like man-o-war and by the wind sailors have sails to aid in movement! 2
Phylum Cnidaria Symbiosis is common with zooxanthellae: 95% of food and formation of calcareous skeleton. Phylum Cnidaria Some have a two phase life cycle! Polyp and medusa Sex: Two phase life cycle (polymorphism)=sessile polyp phase and mobile medusa phase. Sexual rep is usually by medusa (eggs and sperm by broadcast spawning, or internal fertilization). Polyp also undergoes asexual budding Phylum Cnidaria Some have a two phase life cycle! Polyp and medusa Phylum Cnidaria Class Hydrozoa: siphonophores Aurelia: one of our Jellyfish (scyphozoan) 3
Phylum Cnidaria - Class Hydrozoa Phylum Cnidaria, class scyphozoa Jellyfish and friends Stinging cells - unique to Cnidaria Anthozoa - corals and anemones Fluid filled capsule Nematocysts Nematocysts discharge on contact and with other stimuli (e.g. fresh water!) 4
Coral Polyp Zooxanthellae photosynthetic dinoflagellates (Kingdom: Protista) that are adapted to live within corals. Phylum Cnidaria - Class Anthozoa Tentacles Zooxanthellae Mouth Gut Metridium giganteum, Urticina lofotensis, Urticina piscivora White plumed anemone, White spotted rose a., Fish eating anemone Phylum Ctenophora Phylum: Ctenophora Characteristics of Comb Jellies About 100 species - more???? 8 rows of ciliary combs (ctenes) Bi-radial symmetry Cilia beat continuously Light is refracted off the cilia giving a prism-like color effect Respiration occurs at body surface some have tentacles with sticky cells called colloblasts used to capture prey cells and tissues are organized into organs (rudimentary) simple Gut (single opening) 5
Phylum: Ctenophora Natural history of Comb Jellies No segmentation; No circulatory system length from a few mm (sea gooseberry) to 2 meters long (venus s girdle) Most are pelagic, Found in warm and cold oceans - many are deep sea and bioluminescent Carnivores (e.g. eat fish larvae) Hermaphrodites broadcast Lots we don t know! Flatworms: Phylum: Platyhelmenthes Class Turbellaria Phylum Platyhelminthes: flatworms As many as 20,000 species! CNS, Brain (agg. Of nerve cells in head region). Nerve cords and muscular system. Many (such as flukes) are parasites (eg. tapeworms one is 40 feet long in sperm whales) Bilateral Organs and organ systems, nerves, brain, CNS, muscles No skeleton Variety of functions (parasites, free living etc.) Sexual, most have larval stage Flatworms: Phylum: Platyhelmenthes Class Turbellaria 6
Ph Nemertea (ribbon worms), Ph Nematoda (roundworms) Phylum Nematoda (roundworms) Bilateral symmetry dig tract, and true organs. Hydrostatic skeleton Huge #s in sediments, decomposers, parasites, Sexual reproduction with larvae. Can be seen in fish flesh! Lophophorates: bilateral symmetry Bugula turbinata Plumatella fungosa Lichenopora hispida 7
Lophophorates: Lophophore=set of ciliated tentacles arranged in a horseshoe). Suspension feeders, mostly colonial (individual zooids), live in area of low sedimentation Bryozoans (moss animals) Bilateral Unsegmented, colonial. U shaped gut Exoskeleton of a variety of shapes Benthic filterfeeders Sexual and asexual. Phylum Bryozoa: look like colonial hydrozoans. 4000 species, delicate colonies. Retractable lophophore. Zooids show task specialization. Polychaete worms (Phylum Annelida) 8
Phylum Annelida: segmented worms bilateral Segmentation Gut cavity, complex movement and systems. Makes them good crawlers and burrowers. 2 Ventral nerve cords : peristaltic movement. Each segment has kidneys for nitrogenous waste, and parapodia with setae for movement. Closed circulatory system. Have gills Hydrostatic skeleton - many have tubes etc! See ploychaeta: deposit feeders and suspension feeders: active and passive, and carnivorous. Some crawl. Sexual. Trochophore larvae. often timed with phases of moon. Phylum Annelida - Class Polychaeta Class Polychaeta: most annelid species are here. 6,000 sp. Mostly marine. 5-10 cm long. Live singly or in aggregations. Build tubes made with lots of different things. Cilia and mucus aid in feeding. Diopatra ornata Ornate Tube Worm Phylum sipuncula: peanut worms Phylum Sipuncula (peanut worms). All marine. 350 sp, benthic. Most intertidal, few deep sea. Bilateral Unsegmented. Can curl in to look like peanut. Mouth and anus at same end Hydrostatic Burrows (open at one end). Calcarous tubes or burrows. Sexual: gametes released through temporary gonads. External fertilization 9
Ph. Echiura: fat innkeeper worm Phylum Echiura: spoon worms. About 100 sp. Fat innkeeper (Urechis Caupo). Burrow with commenal creatures in mud. Sweep detritus with proboscis and urechis uses a mucus net. Pumps water through burrow and through net. Close relatives of annelids. 10