Animal Diversity

Animal Diversity Campbell Biology 7th ed., Ch. 32, 33 & 34

What is an Animal? • Eukaryote • Multicellular • Heterotroph • Has intercellular junctions • Has muscle and nerve cells for movement and impulse conduction

Symmetry Radial Have top and bottom but no sides Bilateral Have dorsal (superior) and ventral (inferior), anterior (front) and posterior (rear/back) sides Can be divided into 2 equal halves May exhibit cephalization (head) Tissues Arise from germ (embryonic) layers ectoderm, endoderm and mesoderm Body Cavity/coelom Body Plans

Phylum Porifera Live in water Asymmetric body form Lack true tissues and organs Stationary, hermaphrodites Trap food as it passes through sponge body INVERTEBRATES: Sponges

Radial body symmetry Gastrovascularcavity for digestion and material dispersion Either a Polyp (tubular body) with tentacles and mouth extending upward, or Medusa (flattened body) with tentacles and mouth down Tentacles contain a stinging chemical Includes jellies, corals, hydra, anemones Cnidarians

Flatworms • Thin (flattened) bodies, bilateral symmetry • Gas exchange and waste elimination occurs by diffusion • Live in aquatic or damp terrestrial habitats • Size ranges from microscopic to 20 meters long • Most have a gastrovascular cavity • Some have light-sensitive eyespots • Many are pathogenic (internal and external) • Includes planarians, tapeworms

Molluscs • Have a 3-part body plan • Muscular foot usually used for movement • Visceral mass containing internal organs • Mantle draped over the visceral mass, and may secrete a shell • Includes snails, slugs, clams, mussels, scallops, squid, octopi, chambered nautiluses

Annelids Segmented wormsresemble a series of fused rings • Length ranges from 1 mm to 3 m • Includes earthworms, marine segmented worms, leeches • Several layers of muscle permit movement • Most have • Coelom • Closed circulatory system • Ventral nerve cord and a primitive brain • Have several sense organs, including eyes, cells sensitive to light and touch, some have antennae

Arthropods • 2/3 of known animal species are arthropods • Exist in almost every known habitat • Arthropods are segmented, coelomates with an exoskeleton and jointed appendages • They have well developed sense organs, including eyes, olfactory receptors, and antennae for touch and smell • They have open circulatory systems • Included are spiders, scorpions, insects, centipedes, crabs, lobsters

Cheliceriforms • Named for their claw-like feeding appendages • Have 2 body segments, no antennae and usually simple eyes • Most are arachnids • Scorpions, spiders, ticks, mites • Have 4 pairs of legs • Spiders have poison glands in their chelicerae to assist in attacking prey • Spiders also construct silk webs

Insects • 3 body segments: head, thorax, abdomen • Many can fly, with 1 or 2 pair of wings • Have a nervous system ; many have antennae and compound eyes • Open circulatory system • Mouth is specialized for chewing, sucking, lapping or piercing • Many undergo incomplete or complete metamorphosis

Crustaceans • Have branched appendages that are extensively specialized for feeding and locomotion • Include lobsters, crabs, crayfish, shrimp, barnacles and pillbugs • Most are aquatic

Echinoderms Spine Stomach Anus Gills • All are marine • Endoskeleton of limestone covered by a thin skin, bumps and spines • Have a water vascular system made of a central ring canal and radial canals running in grooves down each arm • branches into tube feet that function in movement, feeding, gas exchange, and sensory awareness • Include sea stars, sea urchins, sand dollars, sea cucumbers Central disk Madreporite Digestive glands Radial nerve Ring canal Gonads Ampulla Podium Radial canal Tube feet

VERTEBRATES • Animals with a bony vertebral column and skull • Encloses spinal cord and brain • Most have a mineralized endoskeleton • Most have jaws & paired appendages • Have enhanced sensory organs

Chondrichthyans Sharks, Rays, and their relatives Have a skeleton composed primarily of cartilage Pelvic fins Pectoral fins Southern stingray (Dasyatis americana). Blacktipreef shark (Carcharhinus melanopterus). Chondrichthyans

Clownfish Sea horse Osteichthyes • The vast majority of vertebrates are Osteichthyes • Nearly all have a bony endoskeleton • Most are fish

During metamorphosis, the gills and tail are resorbed, and walking legs develop. Amphibians • Terrestrial (partly), have feet and ears • Class Amphibia includes primarily salamanders, frogs and toads

Wagler’s pit viper (Tropidolaemus wagleri), a snake Reptiles • Includes lizards, snakes, turtles, crocodilians • Reptile scales create a waterproof barrier • Most breathe via lungs • Most lay shelled eggs on land

Birds • Adaptatedfor flight with wings and feathers • Considerable variation in foot and beak structure • Endothermic

Mammals • Have hair and produce milk • Generally have a larger brain than other vertebrates of equivalent size • Monotremesare a small group of egg-laying mammals consisting of echidnas and the platypus • They are found only in Australia and New Guinea • Marsupials – mammals with a pouch – include opossums, kangaroos, and koalas • They are found only in Australia and North and South America

Placental Mammals (Eutherians) • Complete embryonic development within a uterus, joined to the mother by the placenta • Eutherian orders include • Elephants • Rodents • Carnivores • Cetaceans (whales, dolphins) • Horses & rhinos(odd # toes on hooves) • Sheep, pigs, cattle, deer(even # toes on hooves) • Bats • Primates

Animal Diversity