Lab 7 Animals I Porifera Radiata and Introduction

Lab 7: Animals I: Porifera, Radiata, and Introduction to Bilateria

Part A: Sponges (Phylum Porifera) • video • spongin (collagen) No Symmetry (asmmetrical); no true tissue

Task A-1: Sponges (Phylum Porifera) • Slide: Scypha – look for holdfast, osculum • Slide: sponge spiculues • body types: simple, intermediate, complex – draw arrows on Fig. 7 -3; look at specimens

Part B: Phylum Cnidaria • have true tissues • radial symmetry • have stinging cells (cnidocytes) on tentacles and elsewhere • tentacles surround mouth • gastrovascular cavity with extracellular digestion; one opening serves as both mouth and anus • after larval stage (planula), polyp and/or medusa stage(s)

Copyright Ó 2003 Scott A. Bowling Fig. 44. 8

Part B: • Phylum Cnidaria three classes • Hydrozoa – hydroids • Scyphozoa – jellyfish • Anthozoa – sea anemones and corals

Task B-1: Phylum Cnidaria • Hydrozoa – hydroids • usually have both polyp and medusa stages • example: Hydra (solitary freshwater organism) • slides: look for tentacles, bud, cnidocytes, gastrovascular cavity, mouth, epidermis and endodermis (gastrodermis) with mesoglea between • living specimen – note its movement, look for external structures

Task B-1: Phylum Cnidaria • Hydrozoa – hydroids (continued) • example: Obelia (colonial marine organism) • • slides: note structures from Fig. 7 -6 (feeding polyps, reproductive polyps, medusa buds, medusae, tentacles, gonads, mouth, gastrovascular cavity, etc. ) example: Portuguese man-of-war (colonial) • note both polyps and medusae in a colony that has superficial resemblance to a large medusa

Task B-1: Phylum Cnidaria • Scyphozoa – jellyfish • dominant medusae; some have no polyp form • example: preserved specimen – treat it gently! • note tentacles, oral arms, mouth, gastrovascular cavity, gonads, thick jelly-like mesoglea

Task B-1: Phylum Cnidaria • Anthozoa – sea anemones and corals • polyp stage only • sea anemones – very muscular • some sessile, but not all (…see video) • example: preserved specimen (treat gently!) • note mouth, tentacles, pedal disc

Task B-1: Phylum Cnidaria • Anthozoa – sea anemones and corals (continued) • corals • most secrete calcium carbonate exoskeletons • look at dry coral specimens; note distinct cups indicating origins from separate polyps

Part C: • Bilateria – animals with bilateral symmetry • associated with cephalization (forming a true head) • learn dorsal/ventral and anterior/posterior

Fig. 44. 3 b

Part C: • Bilateria different forms based on fluid-filled body cavity • acoelomate – no body cavity • pseudocoelomate – body cavity bound by mesoderm on one side, endoderm on the other • coelomate (or eucoelomate) – “true” body cavity, surrounded by mesoderm on both sides

Fig. 44. 4

Coelomates coelom surrounded by mesodermal tissue (also called eucoelom) l allows for more complex organs, especially digestive system Copyright Ó 2003 Scott A. Bowling l

Part C: Bilateria • body cavities allow many things, such as hydrostatic skeleton, internal organs, circulatory system, etc. • coelom allows for more specialization than pseudocoelom does

Part C: Bilateria • Two major clades within Bilateria: Protostomia (covered in this lab and lab 8) and Deuterostomia (covered in lab 9) • Within Protostomia, two major clades

Part C: Bilateria non-molting protostomes (labs 7 and 8) vs. molting protostomes (lab 8) • Two selected non-molting phyla covered in this lab: • Phylum Platyhelminthes – flatworms • Phylum Annelida – segmented worms

Part C: Phylum Platyhelminthes – flatworms • acoelomate • dorsoventral flattening in most • incomplete digestive tract, when present (combo mouth/anus, just like Cnidarians) • most are parasitic; some are hunters • hermaphroditic • …. video

Task C-1: Phylum Platyhelminthes – flatworms • • 3 classes • Turbellaria • Cestoda – tapeworms • Trematoda – flukes examine specimens and slides, look for structures noted in Figs. 7 -10, 11, and 12 such as ocellus, pharynx, intestine, scolex, proglottids

Part C: Segmented Worms (Phylum Annelida) • segmented – linear repetition of body parts; specialization in some (such as head); often separated by septa • use coelom for hydrostatic skeleton • closed circulatory system • excretory tubules (metanephridia) • most have chitinous bristles (setae) on most segments – for sensing, and locomotion

Task 2: Segmented Worms (Phylum Annelida) • 3 classes • Polychaeta (polychaetes) • Oligochaeta (earthworms) • Hirudinea (leeches)

Task C-2: Segmented Worms (Phylum Annelida) • annelid box and slide: examine the preserved specimens and slide, note the following: • Polychaeta – clamworm: • distinct head with tentacles, eyes, jaws • fleshy parapodia on segments – used for locomotion • compare to plume worm (not in box – demo only)

Task C-2: Segmented Worms (Phylum Annelida) • annelid box and slide: • Oligochaeta – earthworm: • • rub to feel chitinous setae, used for holding to soil clitellum – band used in mating; is nearer to the anterior end of the worm reproductive pores anterior to clitellum (earthworms are hermaphroditic) cross-section slide: compare to Fig. 7 -14, note structures bolded in you manual such as coelom

Task C-2: Segmented Worms (Phylum Annelida) • annelid box: • Hirudinea – leech: • dorsoventral flattening • lack of setae and parapodia • less distinct segmentation • suckers for attaching to host for feeding (leeches are blood-sucking parasites)

TODAY YOU WILL TAKE AN EXIT QUIZ !!!