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 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 Polyp Feeding Polyps on colonial hydroid 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! 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 Stinging cells - unique to Cnidaria Fluid filled capsule Nematocysts Aurelia: one of our Jellyfish (scyphozoan) Nematocysts discharge on contact and with other stimuli (e.g. fresh water!) 2
Coral Polyp Zooxanthellae photosynthetic dinoflagellates (Kingdom: Protista) that are adapted to live within corals. Phylum Cnidaria - Class Anthozoa Colonial cup coral, Orange Cup Coral, Brown Cup Coral Phylum Cnidaria - Class Anthozoa Metridium giganteum, Urticina lofotensis, Urticina piscivora White plumed anemone, White spotted rose a., Fish eating anemone 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) 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! 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 3
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: 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. 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. 4
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). 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 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. Phylum Cheatognatha: arrow worms. Only about 100 sp. Bilateral Unsegmented, flattened, quick movements, small body (high SA/V ratio means they don t have resp. circ or excret. Systems.). Cilia serve to notify them of movements in the water (like shark lateral line system) Hydrostatic Predators, planktonic Hermaphrodites Phylum Mollusca Successful, more species of this phylum than any other in the oceans. Diversity of shape and diversity of habitats that they inhabit is high. 110,000 species: second only to arthropods Soft bodied with a mantle that produces a shell (CaCo 3 ) Unsegmented and bilateral symmetry Foot ventral and muscular for locomotion Radula ribbon of teeth for rasping, made of chitin. Separate mouth and anus Circulatory system most open, cephalpods closed (Blood remains in vessels) Reproduction dioecious and hermaphroditic, most have trochophore larvae to veliger Some are benthic, some are pelagic, and they live from the intertidal to the deep sea. Some are predators, some are herbivores (grazers), while still others are filter feeders. 5
Class Gastropoda "stomach footed" snails, ~ 90,000 species! Nudibranchs, limpets Feed with radula rasping tongue, coiled shell (most), Graze, some are sessile, most are motile Class Bivalvia clams, mussels,oysters ~3000 species 2 shells, crystalline style (enzyme secretion), siphon, foot, gills, pearls laterally compressed, some burrow, bore, or attach to hard substrate. Class Cephalopoda "head foot" ~600 species Siphon for jet propulsion, funnel, ink, pen, beak Active body plan of molluscs octopuses 8 arms, no shell, bottom and crevice dwellers, hunters squid 10 arms, 2 tentalcles, "pen", largest invertebrate... cuttlefish 8 arms, 2 tentacles, cuttle bone Class Polylacophora ~ Chitons, 8 plate like shells, radula, foot ~600 sp Phylum Arthropoda: jointed leg. 1 million species! (most numerous phylum). Includes the insects. Very successful phylum in terms of diversity of species and habitats they live in. They have an exoskeleton of chitin, and the molt their skeleton periodically (like snakes). Subphylum Crustacea: 35,000 species, Includes the copepods, crabs, lobsters, krill, and barnacles. Bilateral symmetry Segmented bodies. Paired appendages (jointed legs). Dorsal (on the back) heart, and ventral (on the stomach) nerve cord. They (crustaceans) have a simple brain, and an open circulatory system. Exoskeleton of chitin which they molt Some are planktonic (like copepods) while others are benthic scavengers and predators (like shrimp and lobsters), and still others are filter feeders (like copepods). They (crustaceans) have separate sexes. Male transfers sperm to female, and she holds the eggs. They have a planktonic nauplius larvae Class Copepoda (oar foot): copepods. Small and planktonic. Major consumers of phytoplankton (mostly diatoms). Class Decapoda (10 feet). Largest class. Crabs, shrimp and lobsters. All (even crabs) have a tail like in the lobster. In the crab it is curled under. You can use it to sex a crab (in the male it is thin while in the female it is wide). Crabs have a high diversity of forms. Decapods are an important food source for humans. Class Isopoda (equal feet): Pill bugs (terrestrial) and kelp isopods are examples of this class. Some are parasitic on fish gills. Others can be seen just above the high tide mark running like big pill bugs with large feet (they are actually marine species ligia). Class Amphipoda (double feet): sand fleas, caprellids (you ll see these later in our float lab), whale lice, and the little organisms that gray whales feed on are amphipods. They can occur in great numbers. Many (like the ones gray whales eat) are benthic and live in soft sediment. Laterally compressed bodies. Class Cirripedia (curled feet): barnacles. Sessile and hermaphroditic. They have the longest penis relative to body size of any animal on earth (over 6 times their body length!). Sessile, filter feed with their feet. 6
Cirripedia: barnacles Echinoderms - spiny skin Deuterostomes: Formation of the mouth second in deuterostomes evolutionarily links echinoderms, hemichordates, and chordates. Primitive echinoderms and pterobranch hemichordates probably arose from an ancestral tentacled filter-feeder, which also gave rise to the chordate line. Phylum Echinodermata ~ 6,000 species living from the intertidal to the very deep sea Radial pentamerous (5 part) symmetry as adults Bilateral symmetry as larvae 3 body cavities (coelomic cavities). Water vascular system: tube feet Pedicellaria Endoskeleton (CaCo 3 ) Poor or absent circulatory system. Non-segmented Most are benthic as adults: filter feeders, grazers, scavengers, detritivores, predators Most have separate sexes - broadcast and brood Phylum Echinodermata Class Asteroidea (star-like): Sea stars (starfish). About 1600 species. Some have as many as 50 arms! Stomach sticks out from body for external digestion. They can stick this stomach into a bivalve (clam) shell and begin digesting it! Class Echinoidea (hedgehog like). Sea urchins and sand dollars, about 900 species. Very much like sea stars (in terms of body organization), but have no arms. In some urchins, the mouth (Aristotle s lantern), is adapted for grazing on algae. Sand dollars live in soft sediment and filter feed with tube feet and move with their spines (opposite from other echinoderms). Phylum Echinodermata Figure 33.37 Anatomy of a sea star Class Ophiuroidea (snake form). Brittle stars and basket stars, about 2000 species. Their arms an wave and move like a snake. They use them for movement and filter feeding (the tube feet do the actual feeding). Class Holothuroidea. Sea cucumbers. These lack actual spines, but have soft spiny projections. Many are eaten (there is quite a large fishery for them). There are about 1,100 species, and some are found very deep. They are filter feeders and deposit feeders (literally eat the mud or sand and digest organic matter out of it). 7
Phylum Chordata notochord flexible rod support between nerve cord and gut Dorsal hollow nerve cord forms from the ectoderm and rolls into a tube dorsal to the notochord Phylum Chordata Pharyngeal slits small opening at end of gut or pharynx (nearest to mouth). Muscular tail projecting beyond (posterior to) the anus Phylum Chordata Other characteristics: bilateral symmetry Segmentation three germ layers and a welldeveloped coelom. ventral heart, with dorsal and ventral blood vessels and a closed circulatory system complete digestive system bony or cartilaginous endoskeleton usually present SP Urohordata: tunicates, larvaceans, salps Cellulose tunic S.P Urochordata Class Larvacea larvaceans Mouth opens to a basket-like pharynx Pharyngeal gill slits Free swimming larval form 8