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KINGDOM ANIMALIA (Animals) Campbell, Chapters 33 & 34 What are the characteristics and evolutionary trends of the following phyla and classes? -Nematoda: roundworms -Arthropoda: arthropods. -Arachnida: spiders, scorpions. -Crustacea: crustaceans. -Insecta: insects. -Echinodermata: echinoderms. -Asteroidea: sea stars. -Holothuroidea: sea cucumbers. -Echinoidea: sea urchins. -Chordata: chordates. -Urochordata: tunicates or sea squirts. -Cephalochordata: lancelets. -Vertebrata: vertebrates. -Myxini: hagfishes. -Cephalaspidomorphi: lampreys. -Chondrichthyes: sharks and rays. -Actinopterygii: ray-finned fishes. -Amphibia: frogs, toads and salamanders. -Mammalia: mammals. -Testudines: turtles. -Lepidosauria: lizards and snakes. -Aves: birds. Secrete external skeletons, molt. Phylum Nematoda “thread form”: round worms >90,000 spp, in aquatic habitats, wet soils, inside plants and animals. -Length: <1 mm to over 1 m. -Cylindrical body, pseudocoelom. -Complete digestive tract (tube with mouth and anus). -Eat animals; algae and fungi; detritus; parasites of plants and animals. -Longitudinal muscles, produce a thrashing motion. -Ecdysozoa: molt a tough exoskeleton called cuticle. Segmentation & appendages: further allowed division of functions and a great diversification of forms. Cuticle: strength and impermeability solved desiccation and structural support > land. Flight: allowed insects to escape predators, find food and mates, and disperse to new habitats. Phylum Arthropoda- “joint foot”: arthropods -Over one million species, most of them insects. The most diverse, widely distributed and abundant of all animal phyla. -Length: 0.1 mm to 1.2 m. -Segmentation, hard exosqueleton (external skeleton), jointed appendages. -Exoskeleton called cuticle, made of protein and chitin. Relatively impermeable to water; strong, to protect and allow muscle attachment. -Ecdysis (molt cuticle). -Well-developed muscles and sensory organs for vision, taste, smell and touch. -Extensive cephalization (concentration of sensory equipment in the anterior end of the body). -Many species have compound eyes (composed of many independent visual units). Arachnida -Mostly terrestrial. -Cephalothorax (head and thorax as one region) with six pairs of appendages: chelicerae (a pair of clawlike feeding appendages), pedipalps (a pair of appendages usually functioning in sensing or feeding) and four pairs of legs. -Spiders are carnivores that use their chelicerae to inject poison into and masticate (chew) their prey; they spill digestive juices and suck up the liquid meal. -Many spiders have the unique adaptation of catching flying insects by stringing webs of silk, a protein produced as a liquid by special abdominal glands. -Scorpions are nocturnal carnivores, pedipalps modified as pincers for defense and capture of food; the tip of the tail has a poisonous stinger. -Ticks and mites are parasites in vertebrates and invertebrates. -Mostly marine. Crustacea -Multiple appendages extensively specialized. -The only arthropods with two pairs of antennae. -Three or more pairs of appendages modified as mouthparts. -Three or more pairs of legs. -Filter-feeders, plankton eaters, carnivorous, detritus eaters, parasites, scavengers. -Crabs, lobsters, crayfish, shrimp, isopods, barnacles, copepods. Phylum Echinodermata “spiny skin”: echinoderms -About 7,000 species, all marine, in six classes. Length: 1 mm to 1 m. -Pentamerous radial symmetry in adults: the body can be divided into five parts arranged around a central axis. -Endoskeleton (internal skeleton) of movable or fixed plates (ossicles) and projecting elements (spines or tubercles). -Unique water-vascular system, fluid-filled tubes beginning in the madreporite and ending in blind-ending tube feet. -Tube feet used for locomotion, food gathering, and gas exchange. -Many have pedicellaria, thin, flexible stalks manipulated by muscles and with three jaws apiece that offer protection. Endoskeleton, functionally similar to arthropod exoskeleton: a hard shell encasing the body, still limits body size. Asteroidea Echinoidea Holothuroidea Phylum Chordata: chordates -Length: <1 mm to 30 m. -Segmentation, muscles arranged in segmented blocks. -Jointed appendages. -Most with a truly internal and jointed skeleton, differing from that of echinoderms. -Notochord. Longitudinal, flexible rod between digestive tube & nerve cord. -Dorsal, hollow nerve cord. Vertebrates: becomes brain and spinal cord. -Pharyngeal slits. Water exits w/o going through digestive tube. Filter feeding invertebrate chordates; gas exchange, jaw support, hearing in vertebrates. -Muscular, postanal tail. Provides much of the propulsive force. Subphylum Urochordata -Most sessile marine animals, some are colonial. -Water enters through incurrent siphon, passes through pharyngeal slits into atrium and exits through an excurrent siphon. -Filter-feeders, trap food with a mucous net. -Animal encased in a tunic made of celluloselike carbohydrate. -Larvae presents all four chordate characteristics. Subphylum Cephalochordata -Small, burrowing animals that live along sea coasts. -Adults possess all four chordate traits. -Filter feeders, water exits through pharyngeal slits. -Muscles serially arranged like rows of chevron (<<<<<<). -Sensory tentacles around mouth. Unique group of embryonic cells that participate in the development of various structures. (CRANIATES). Myxini -All marine. Mostly bottom-dwelling scavengers. -Slime glands along the sides to repel others and for protection. -Cartilaginous skeleton. -Mostly blind, well-developed sense of smell. Hagfishes. Vertebral column, encloses and protects nerve cord; provides support and makes large body size and fast movement possible. Cephalaspidomorphi -Marine and freshwater environments. -Clamp round mouth onto flank of live fish, use rasping tongue to penetrate skin and ingest blood. -Cartilaginous skeleton. -No paired appendages, no jaws. -Lampreys. Jaws and mineralized teeth, allow to firmly grip and slice food items, and eat prey that until then was inaccessible. Paired appendages (fins), allow accurate maneuvering in the aquatic environment while swimming. Chondrichthyes -Marine and freshwater environments. -Cartilaginous skeleton, in most strengthened and with bony teeth. -Skin covered by tooth-like scales. Sharks, rays, mantas, chimaeras. -Rays: flattened bottom-dwellers that crush invertebrates with jaws, some live in open water and filter food -Sharks: streamlined bodies and well-developed jaws and fins. -Most carnivores, some filter-feeders. -Sharp black and white vision and well-developed senses of smell and electric fields in the head and of water pressure along the flanks (lateral line system). Lungs or lung derivatives, in most fishes developed into swim bladder to control buoyancy and maintain constant depth without moving; in other organisms allowed obtaining oxygen from the air and thus exploiting land environments. Actinopterygii -Marine and freshwater environments. -Ossified skeleton, skin often covered by flattened, bony scales. -Skin glands secrete a mucus that reduces drag during swimming. -Lateral line system and jaws; fins mainly supported by flexible rays. -A protective flap called the operculum covers the gills. -A variety of feeding mechanisms. -Part of the “bony fishes”. Legs, allow better locomotion in terrestrial and very shallow water environments. Amphibia -Aquatic and terrestrial environments. -Ossified skeleton. -Moist skin, legs (secondarily lost in some species) and lungs (usually). -Skin glands secrete distasteful or poisonous mucus as a protection against predators. -Mostly carnivores. -Frogs, toads, salamanders, and newts. -Still tied to water for reproduction, most abundant in damp habitats. -Many go through a metamorphosis. http://elib.cs.berkeley.edu/aw/ Amniotic egg allowed terrestrial vertebrates to complete their life cycle on land and sever last ties with aquatic past. Milk, provide the ability to adequately nourish offspring. Mammalia -Mostly terrestrial, some marine and freshwater. -Skin covered with hair (reduced or absent in some species) and mammary glands in the females to provide milk to the young. -Legs lost in some. -Amniote egg, but the embryo does not develop a shell. -Variety of feeding mechanisms. Testudines -Terrestrial, marine and freshwater environments. -Characterized by a hard shell, to which vertebrae and ribs are fused. Amniote egg with a shell. -Sharp, horny beak without teeth. -Most are carnivorous or eat plants or algae. -Turtles, sea turtles, tortoises. Lepidosauria -Terrestrial, some in marine and freshwater environments. -Legs lost in snakes. Amniote egg with a shell. -Loose articulated jaws to swallow large prey, some inject poison. -Most are carnivores with acute chemical (through the flicking tongue), vibration and heat sensors. Tuataras, lizards and snakes. Feathers, provide ability to fly and insulation. Aves -Mostly terrestrial, some marine and freshwater. -Skin covered with feathers, light and hollow skeleton; flight adaptations. -Legs and wings, most species move by flying. -Amniote egg with a shell. -Mouth developed into a beak. -A variety of feeding mechanisms. SUMMARY General traits of reviewed phyla, subphyla and classes. Important evolutionary trends in body plan: -Endoskeleton: Echinoderms. -Notochord, nerve cord, tail, pharyngeal slits: Chordates. -Cranium, brain development, neural crest cells: Hagfishes. -Vertebral column: Vertebrates. -Jaws, 2 sets of paired appendages, mineralized skeleton and teeth: Sharks and rays. -Lungs or lung-derivatives: “Bony fishes” -Legs: Amphibians. -Amniote egg: Mammals, turtles, snakes and lizards, birds. -Milk: Mammals. -Feathers: Birds. These trends helped animals adapt to different environments or exploit the same environment in a different manner.