Animals

Biology

Donald Winslow

8 April 2011

Kingdom Animalia

• Sponges (invertebrate)

• Radially symmetrical animals (invertebrate)

• Bilaterally symmetrical animals– Most invertebrate– Most of Phylum Chordata are vertebrate

Patterns of symmetry

Bilateral symmetry Radial symmetry

Photo by Richard Snow

Phylum Porifera (sponges)

• Multicellular, cell-tissue organization

• Mostly marine, some freshwater

• Radially symmetrical or asymmetrical

• Flagellated larvae (parenchymula)

• Sessile adults

• Maintain internal water currents for feeding

• No nervous system or sensory organs

Radiate animals

• Phylum Cnidaria– Class Hydrozoa– Class Scyphozoa (true jellyfish)– Class Staurozoa– Class Cubozoa– Class Anthozoa (sea anemones & corals)

• Phylum Ctenophora (comb jellies)

Bilateria

• Bilateral symmetry & cephalization

• Phylum Acoelomorpha

• Superphylum Protostomia– Mouth develops from blastopore (1st opening)

• Superphylum Deuterostomia– Anus develops from blastopore & mouth later

Phylum Platyhelminthes

• “flatworms”

• Free-living & parasitic species

• Anterior ganglia, ladder-type NS

• Sensory organs

• Excretory system

• Usually hermaphroditic & outcrossing

• Parasitic spp w/ complex life-cycles

Phylum Nematoda

• Longitudinal muscles & muscular pharynx

• Anterior & posterior nerves, sense organs

• Usually separate sexes

• Females larger than males

• Microscopic eggs

Phylum Mollusca

• Coelom usually only around heart

• Unsegmented with organ systems

• Trochophore & veliger larvae in many

• Gills (ctenidia) or lung

• Circulatory system usually open

• Variation in body size

• Mantle, mantle cavity, shell, foot, head

Phylum Mollusca

• Classes Caudofoveata & Solenogastres

• Class Monoplacophora—one shell plate

• Class Polyplacophora—8 shell plates

• Class Scaphopoda—tusk shells

• Class Gastropoda—snails & slugs

• Class Bivalvia—clams, mussels, etc.

• Class Cephalopoda—squid, octopus, etc.

Phylum Annelida

• Segmented worms

• Marine polychaetes

• Earthworms & other oligochaetes

• Leeches

Phylum Arthropoda

• Diversity & abundance

• Exoskeleton & chitin, ecdysis (molting)

• Somites, tagmata, jointed appendages

• Complex muscular system, no cilia

• Open circulatory system & hemocoel

• Mouthparts, complete digestive tract

• Excretory glands & Malpighian tubules

Phylum Arthropoda

• Subphylum Trilobita– extinct marine animals

• Subphylum Myriapoda– Centipedes & millipedes

• Subphylum Chelicerata– Horseshoe crabs, spiders, scorpions, etc.

• Subphylum Crustacea—crustaceans

• Subphylum Hexapoda—insects

Phylum Echinodermata

• Sea stars (“starfish”)

• Sea urchins and sand dollars

• Bristle stars

• Sea cucumbers

• Crinoids

Phylum Chordata

• Subphylum Urochordata—tunicates

• Subphylum Cephalochordata—lancelets

• Subphylum Vertebrata (Craniata)– The fishes (paraphyletic)– Class Amphibia (paraphyletic)– Class Reptilia (paraphyletic)– Class Aves (monophyletic)– Class Mammalia (monophyletic)

Characteristics of chordates

• Notocord, often endoskeleton

• Dorsal hollow nerve cords

• Often predators

• Pharyngeal gill slits, often become gills

• Paired appendages—fins, limbs, wings

• Postanal tail

• Segmented myotomes

Spotted Gar

Class Amphibia

Can use land, but usually tied to water for reproductionWebbed feet, forelimb usually with 4 digitsSkin smooth & moist with many glands, chromatophores, no scalesRespiration by skin, gills, and/or lungs, 3-chambered heart (2 atria)Ectothermal, paired mesonephric kidneys, urea main nitrogenous wasteSeparate sexes, usually oviparous, mesolecithal eggs laid in waterMetamorphosisOrder Apoda (caecilians)

No legs, tropical forests, internal fertilization, egg-guardingOrder Caudata or Urodela (salamanders)

Internal fertilization, female picks up spermatophoreAquatic species metamorphic, gills as larvae & lungs as adults Terrestrial species develop directly; plethontids breathe thru skinPaedomorphic species (mudpuppy, axolotl) retain gills as adults American newts: aquatic larvae, terrestrial efts, aquatic adultsParental care

Order Anura (frogs & toads)

Order Anura (frogs & toads)

VocalizationExternal fertilization during amplexusEgg, tadpole stages, adult

Family RanidaeBullfrog, leopard frog, etc.

Family HylidaeTreefrogs

Family BufonidaeToads

Class Reptilia (paraphyletic taxon)

Shelled, amniotic eggExtra-embryonic membranes

Amnion, chorion, allantoisMost species entirely terrestrialDry, scaly skin, chromatophoresPowerful jaws, ectothermicInternal fertilization, separate sexesAdaptations to conserve waterHigher blood pressure than amphibiansNo gills, respiration usually by lungsMain nitrogenous waste is uric acid

Class Reptilia

Order Testudines (turtles)Superorder Lepidosauria

Order SquamataOrder Sphenodonta

Superorder ArchosauriaOrder Crocodilia

Characteristics of modern birds

• Long neck

• Wings

• Feathers

• Pneumatized skeleton

• Beak

• No teeth

• Short tail (pygostyle)

Avian taxonomy

– Order Podicipediformes (grebes)– Order Pelecaniformes (pelicans, cormorants,

etc)– Order Ciconiiformes (herons, storks, vultures,

etc)– Order Anseriformes (swans, ducks, geese)– Order Falconiformes (hawks, eagles, kites,

falcons)– Order Piciformes (woodpeckers)– Order Passeriformes (songbirds)

Characteristics of mammals

Hair, keratin, follicles Glands: sweat, scent, sebaceous, and

mammary Teeth diphyodont & usually heterodont Secondary palate, eyelids & external ears 4 limbs, many types of locomotion 4-chambered heart; nonucleated red blood

cells Muscular diaphragm, often horns or antlers