BIO 120: Ch. 17- Animals

Animals

Cells lack cell walls. Eukaryotic, multicellular, heterotrophic. Obtain nutrients by eating- Fungi do not eat, they absorb nutrients.

Animals as diploid

Haploid gametes- egg and sperm fuse to form diploid zygote, embryo can turn directly into adult (vertebrates), or go through metamorphosis (egg, larvae, adult)

Body Plan

Structural complexity- differentiated cells, tissues, organs. Symmetry- asymmetry, radial (many immobile), bilateral (nerve center near sense organs, aids movement)

Body Cavity

Fluid filled space. Separates digestive tract from body wall. Organs grow and move independently of body wall

Phylum Porifera - Sponges

Now broken into several phyla. No true tissue- differentiated cell types. Asymmetrical. Water drawn into body. Food particles filtered

Phylum Cnidaria – Jellyfish, Coral, Hydras, Sea Anemones

True tissues – no organs. Radial symmetry. Tentacles with stinging cells (Cnidocytes). Blind sac digestive system (Mouth and anus – same opening)

Phylum Platyhelminthes – Flatworms

Flat or ribbon shaped worms. Many parasitic- blood flukes, tapeworms (up to 20m long in humans)

Phylum – Nematoda - Roundworms

Cylindrical unsegmented body. Pseudocoelom. Aquatic habitats. Can be 1m long. 50 parasitic species infect humans

Phylum Annelida – Segmented Worms

Body segmentation- repeated segments. Complete digestive tract. Coelom. Earthworms. Polychaetes – marine worms (Hard bristles). Leeches – most species free living carnivores

Molluscs – Snails, Slugs, Oysters, Clams, Octopuses, Squids

True Organs. True coelom. Soft bodied- many have shell. Muscular foot. Visceral mass- organs. Mantle – produces shell. Mostly marine

Molluscs – Gastropods - Snails

Single shell. Eat with radula- scraping “tongue”. ¾ of molluscs

Molluscs – Bivalves – Clams, mussels

Shell divided into 2 halves- hinged together. Most sedentary

Molluscs – Cephalopods – Squids, Octopuses, Cuttlefish, Nautilis

Small shell. Large brains. Sophisticated senses

Phylum Arthropoda – Arthropods

Segmented animals. Segments are specialized- diversity of appendages. Exoskeleton- chitin, molting necessary for growth

Arthropods - Arachnids

Scorpions, spiders, ticks, mites. Majority terrestrial. 4 pairs of legs. 2 feeding appendages

Arthropods - Crustaceans

Crabs, lobster, crayfish, shrimps, barnacles, pill bugs. Many appendages. Nearly all aquatic

Arthropods- Millipedes & Centipedes

Millipedes -2 pairs of legs/segment. Centipedes – 1 pair/segment- venomous

Arthropods - Insects

Largest group of arthropods. 3 body parts- head, thorax, abdomen. 3 pairs of legs. 1 or 2 pairs of wings- flight – key to success (escape, find food and mates, dispersal)

Importance of Insects

Products- honey, wax, shellac, silk, dye. Food- high protein content, cultures with little livestock or fish

Insect diversity

Outnumbers all life combined. Live in almost all terrestrial habitats. Rare in ocean

Insect Growth

Metamorphosis- egg, larvae, pupae, adult (many variations). Adult usually specialized for dispersal & reproduction

Phylum – Echinodermata – Starfish, sea urchins, sea cucumbers, sand dollars

Pentaradial symmetry- larvae are bilateral. Endoskeleton- calcium plates. Entirely marine. Water vascular system- act as muscles, don’t tire

Phylum Chordata – Tunicates, Hagfishes, Vertebrates

4 characteristics. Dorsal, hollow nerve chord (Spinal cord). Notochord- backbone. Pharyngeal slits- gills, grooves in mouth. Post anal tail- tail past anus. Always present in embryo

Chordata - Fishes

Jawless Fishes- hag fish, lamprey. Cartilaginous fishes- Sharks and rays, Cartilage – no bones. Bony Fishes- calcium hardened skeleton, ray finned, Lobe finned

Chordata - Amphibians

Frogs, toads, salamanders, caecilians. Aquatic and terrestrial life. Metamorphosis- tadpoles. Breath through skin and lungs. Tetrapods (four feet)- Amphibians, reptiles, mammals

Chordata - Reptiles

Amniotic egg- self-contained habitat, able to survive in dry climates. Scaled waterproof skin. Ectotherm- Cold blooded, ~10 20% of the caloric requirement of mammals

Chordata – Reptiles - Birds

Distinct lineage of reptiles. Therapods – 2 legged dinosaurs. Flight- almost all birds can fly, Feathers – adapted scales. Endotherms- Require more calories, metabolic heat maintains body temperature

Chordata - Mammals

2 Distinct traits- hair, mammary Glands. 3 groups: Monotremes- lay eggs (Platypus, echidna). Marsupials- pouched mammals, birth tiny young, attach to nipples in pouch. Placental Mammals- placenta provides long gestation, fully developed at birth