Lab 7: Lab 7: Animals I: Porifera, Animals I: Porifera,

Radiata, and Radiata, and Introduction to Introduction to

BilateriaBilateria

• video

• spongin (collagen)

Part A: Sponges (Phylum Porifera)

No Symmetry No Symmetry (asmmetrical); no (asmmetrical); no

true tissuetrue 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

CoelomatesCoelomates coelomcoelom surrounded by mesodermal surrounded by mesodermal

tissue (also called eucoelom)tissue (also called eucoelom)

allows for more complex organs, allows for more complex organs, especially digestive systemespecially 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)

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