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

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

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

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) Part B:Phylum Cnidaria

Copyright  2003 Scott A. Bowling Fig. 44.8

three classes Hydrozoa – hydroids Scyphozoa – jellyfish Anthozoa – sea anemones and corals Part B: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 Task B-1:Phylum Cnidaria

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

Fig. 44.3b

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 Part C:Bilateria

Fig. 44.4

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

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:Bilateria

acoelomate dorsoventral flattening in most incomplete digestive tract, when present (combo mouth/anus, just like Cnidarians) most are parasitic; some are hunters hermaphroditic ….video Part C: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 Task C-1: Phylum Platyhelminthes – flatworms

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 Part C: Segmented Worms (Phylum Annelida)

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

TODAY YOU WILL TAKE AN EXIT QUIZ !!!