Introduction to Animal Phyla Phyla Calcarea and Silicea

Introduction to Animal Phyla

Phyla Calcarea and Silicea • Sponges used to be classified in one Phylum = Porifera Pore-bearing • All aquatic • Have pores (ostia) that water flows through • Vary in size and shape – radial or asymmetrical

• Cellular level of organization – no tissues • Multicellular: body a loose aggregation of cells • Intracellular digestion • Excretion and respiration by diffusion • Sessile adults • Asexual reproduction by buds or gemmules • Sexual reproduction – eggs and sperm • Free-swimming larvae

Phylum Cnidaria nettles • Includes: hydra, jellyfish, coral, sea anemones • All aquatic • Radial symmetry • Two body forms • Polyp: sessile (cannot move) • Medusa: free swimming • Tentacles with cnidocytes that contain stinging organelles called nematocytes

• Diploblastic – two germ layers (endo- and ectoderm) with mesoglea • Gastrovascular cavity; extracellular digestion • Nerve net and primitive muscular system • Asexual reproduction by budding • Sexual forms either monoecious or dioecious – planula larva

Phylum Platyhelminthes flat-worms • Cell-tissue level of organization – most systems incomplete or lacking • Body flattened dorsoventrally • Bilateral symmetry • Classes Monogenea Trematoda and Cestoda are entirely parasitic • Class Tubellaria – free-living

• Triploblastic – three germ layers • Acoelomate – no body cavity between the mesoderm and endoderm • Sexual reproduction by gametes – most forms monoecious (separate sexes) • No asexual reproduction • Complex life cycles with multiple hosts in parasitic forms

Phylum Nematoda Thread • Roundworms • Organ-system level of organization • Body round slender tubelike, tapered at both ends • Bilateral symmetry • Mostly free-living in soil or water; some parasitic forms (Ascaris)

• Triploblastic – three germ layers • Pseudocoelomate – body cavity in between the mesoderm and endoderm • Body covered with a secreted, flexible, nonliving cuticle • Sexual reproduction with gametes – dioecious (male and female forms) • No asexual reproduction

Phylum Annelida Little rings • • Segmented worms Bilateral symmetry • Two major classes 1. 2. Oligochaeta (earthworm) Hirudinea – – – Includes leeches Freshwater parasites Secrete enzyme to prevent blood clotting in host

Mollusks • • • Phylum = Mollusca Includes oysters, clams, snails and octopus Three classes 1. Bivalvia – clams, two shells 2. Gastropoda – snails, single shell – Largest group – – Most advanced Mouth surrounded by tentacles 3. Cephalopoda – octopus, no shell

Echinoderms – spiny skin • Phylum Echinodermata includes starfish, sea urchins, sea cucumbers and sand dollars • Have internal skeletons that consists of calcified plates embedded in body wall • Radial symmetry • Spiny projections on plates stick through skin. • Have an oral and aboral surface

Phylum: Arthropoda • Most successful and abundant phylum of animals • 1 million known species (400, 000 plants, 200, 000 all other animals)

5 classes of arthropods 1. 2. 3. 4. 5. Crustacea – lobsters etc. Chilopoda - centipedes Diplopoda - millipedes Arachnida - spiders Insecta - bugs

Common Features of all Arthropods 1. Jointed legs 2. Exoskeletons made of protein and chitin (hard and lightweight but must molt) 3. Segmented, most have: 1. Head 2. Thorax 3. Abdomen 4. Well developed nervous system 5. Open circulatory system

Centipedes • Class: Chilopoda • Poison claws on first segment • Body segments have one pair of legs • Feed on insects

Millipedes • Class: Diplopoda • Body segments have two pairs of legs • No poison claws • Feed on decaying plants • May roll into ball or use “stink” glands when disturbed

Spiders, ticks, mites, scorpions • Class Arachnida • Most live on land resemble insects • Book lungs for gas exchange • Some have spinnerets for spinning silk (web) • 8 legs

Insects are successful because: • Only invertebrate that can fly • Tremendous variation and adaptations for feeding and reproduction, such as: • Mouthparts • Body form • Legs • High rate of reproduction and a short life cycle • Small

Metamorphosis • Distinct changes as an animal develops from an egg to an adult • Incomplete (grasshoppers and crickets) eggs nymphs adult • Complete (moths, butterflies, beetles, bees) eggs larva pupa adult

Entomology – the study of insects • Bad: • Billions of dollars in damage to crops • Transmit animal and plant diseases • Insecticide poisons the environment • Sting and bite • Good • Pollinate crops • Destroy harmful insects • Make honey and other products

Clam Dissection (pg 739) 1. 2. Find the valve adductor muscles. To open the shell, you must CAREFULLY cut these muscles. Once open – make two drawings 1. 2. 3. Internal anatomy Draw before you cut it open Label 10 items total.

Crayfish Dissection 1. External anatomy – draw and label ten items 2. To open crayfish you must remove the carapace: Most of the body organs are located in the cephalothorax, the abdomen is mostly muscle. Make cuts 1 cm on each side of the midline toward the eyes. Snip between the two cuts and remove the strip of carapace. 3. Internal anatomy – draw and label five to ten items 4. Look at any part of the crayfish with the dissection scope. Make a drawing and label what it is.

Grasshopper Dissection 1. 2. External Anatomy – draw and label 10 items To open grasshopper up: • 3. 4. Cut off the wings and legs. Carefully open the exoskeleton. Internal Anatomy – draw and label 5 items, is it male or female? Make third drawing using the dissection scope. Label what it is.