Animal Diversity (1 &) 2 Multicellular, eukaryotic, heterotrophic organisms that feed by INGESTION

Body symmetry Radial symmetryBilateral symmetry

Anterior Ventral Dorsal Posterior

Tissue organization 2 tissue layers = Radially symmetric 3 tissue layers = Bilaterally symmetric

Two tissue layers: Endoderm and Ectoderm

Ectoderm Endoderm Gut Ectoderm Endoderm Gut Ex: Hydra

Three tissue layers: Ectoderm, Mesoderm, Endoderm

Ectoderm: External Layer Skin cells of epidermis Neurons of brain Mesoderm: Middle Layer Cardiac muscle, Skeletal muscle,Kidney cells, Red blood cells, Smooth muscle in gut Endoderm: Internal Layer Lung (Alveolar) cells Thyroid cells Pancreatic cells

Body cavity Acoelomate Pseudocoelomate Eucoelomate

Other characteristics: Openings into digestive tract: One opening or tube within a tube? Open vs. closed circulatory system Organs for gas exchange Organs for excretion Endoskeleton, exoskeleton, hydrostatic skeleton? Segmentation

Porifera (i.e. sponges)

Cnidaria (e.g. Hydra, sea anemones, jellyfish) 2 tissue layers

Platyhelminthes (Flatworms) 3 tissue layers Acoelomate unsegmented No internal organs = must be flat to allow O2 and nutrients in via diffusion Most are parasitic – Schistosomiasis is a disease caused by these guys. Tapeworm too.

Annelida (Clamworms and earthworms) Segmentation! Organs! They’re hydrostatic!

Annelida (Clamworms and earthworms)

Mollusca More than 85,000 species!

Characteristics of most molluscs: Hard external shell for protection Mantle (excretes shell) Visceral mass Muscular foot for locomotion Snail radula!

Ex: cuttlefish

Adductor muscles are well- developed in scallops because they’re active swimmers. (They’re also tasty) Basic bivalve anatomy

Onwards! …to Ecdysozoa = molting animals (Nematoda and Arthropoda) Body covering = cuticle = exoskeleton

Nematoda Most abundant animal on Earth Pseudocoelomate Up to a million different species (only like 50k described) 15,000 species are described as parasitic Sheds proteinaceous cuticle LOTS of investment in reproductive organs

Arthropoda Animals with exoskeleton, segmented body, and jointed appendages Exoskeleton is periodically shed Four subphyla: Cheliceriformes, Myriapoda, Crustacea, Hexapoda Exoskeleton is mainly chitin First organisms to fly – unoccupied niche (air) allowed for massive radiation

Cheliceriformes No antennae, no jaws Pincer-like appendages called chelicera used for grasping and fragmenting food

Myriapoda Millipedes 2 pairs of legs per segment Detritivores Centipedes 1 pair of legs per segment Predators

Crustacea Biramous (two-parted) limbs (even barnacles) Most are free-living aquatic animals Some (e.g. pill bugs) are terrestrial Some (e.g. barnacles) are sessile Ex: Crustacean claws branch into 2 segments

Hexapoda: Six-legged arthropods

External insect anatomy 3 distinct body units: head, thorax, and abdomen

Insect head: Search for: compound eyes, ocelli, antennae, labrum, mouthparts

Insect mouthparts: Mandible, maxilla, labium Chewing mouthparts (e.g. grasshopper) Evolution of mouthpart morphology A: Chewing B: Lapping (e.g. bee) C: Siphoning (e.g. moth) D: Sucking (e.g. mosquito)

Arthropod respiration: Tracheal system

No labs next week. Then only two more labs: - Animal Diversity 3 (chordates and starfish) - and then a final lab practical (no lecture for the last lab) I will post a study guide this week on thinkbiologically.com Don’t forget to turn in your reports! Lots to do today! Have fun! Final notes: