Biology 1120 - Lab 23

1120 Lab 23 - Invertebrate Coelomates

Dissection PDFs on D2L

Phylum->	Annelida	Arthropoda	Mollusca	Echinodermata
Features	segmented worms	largest # insects, spiders, crabs	2nd largest clams, snails, squid	Sea stars, sand dollars
Symmetry	Bilateral	Bilateral	Bilateral	Larvae - Bilateral Adults - radial
Cephalization	Present	Present	Present	Absent
Segmentation	Present	Present	Absent	Absent
Digestive sys.	Complete	Complete	Complete	Complete
Circulatory sys.	Closed	Open	Usually Open	Absent
Respiratory sys.	Absent	Tracheae, gills, book lungs	Lungs, gills	Tube feet, skin gill respiratory tree
Excretory sys.	Nephridia	Nephridia-like glands	Nephridia	Absent
Reproduction	Sexual, some hermaphroditic	Usually sexual	Sexual, some hermaphroditic	Sexual, some hermaphroditic
Embryonic dev.	Protostome	Protostome	Protostome	Deuterostome
Other	Clitellum	Sexual dimorphism	Umbo (clams)	Water vascular system
Table largely stolen from Dr. Shelby

All have True Coelom
- Digestive system and body wall move independently
- Complex Internal Organs
Bilateral - for at least part of their life cycle

Segmented worms like earthworms and leeches - muscles work against fluid-filled coelom to changes width and length for movement.
Closed circulatory system.
Dissect Earthworm - Clitellum (cigar band shaped copulatory structure ), pharynx, esophagus, crop, gizzard, intestine, dorsal blood vessel, aortic arches (hearts), brain, ventral nerve cord, seminal vesicles/recptacles (gonads)

paired jointed appendages, chitinous exoskeleton (you don't have to know subphylum names)

Subphylum Unramamia
- Classs Insecta - Insects
- Millipedes
- Centipedes
Subphylum Chelcerata
- Class Arachnida - Spiders and scorpions
- Merostomata - Horseshoe Crab
Subphylum Crustacea
- Crabs
- Shrimp
- Barnacles
- Dissect Crayfish - Gills, heart (model), stomach, digestive glands, green glands (illust), gastric mill, intestine.

Bivalvia - marine and fresh water filter feeders - clams and scallops exoskeleton, no head, open circulatory system, adductor muscles
Gastropoda - marine, fresh-water and terrestrial - snails (coiled shell)
Cephalopoda - predators such as squid, octopi, cuttlefish, nautiluses - Tentacles around a head Preserved Squid
Dissect Clam - Know Umbo, dorsal, ventral, anterior, posterior, adductor muscles, mantle, foot, gills, visceral mass, pericardial sac, heart

view specimens and starfish model
Dissect Starfish - External - Tube feet, mouth, mandreporite (sieve plate). Internal - Stomach, digestive glands, gonads (model) radial canals.

General characteristics (level of organization, symmetry, body plan, etc) of organisms in each of the four phyla covered in this lab (Mollusks, Annelids, Arthropods, and Echinoderms).
Which phylum each animal that we dissected represents.
Identification of the following on a clam (dissection or color illustration): dorsal, ventral, anterior, posterior, umbo, anterior adductor muscle, posterior adductor muscle, heart inside the pericardial sac, mantle, gills, foot, and visceral mass (area where the digestive organs are located).
Identification of the following on an earthworm (dissection, color illustration or model): Clitellum (external), pharynx, esophagus, crop (soft), gizzard (firm), intestine, dorsal blood vessel, aortic arches (hearts), brain, ventral nerve cord, seminal vesicles/receptacles (gonads).
Identification of the following on a crayfish (dissection, color illustration or model): dorsal, ventral, eye, antennae, swimmerets, gills, stomach, gastric mill, digestive glands, heart (model), green glands (illust), intestine.
Identification of the following on a starfish (dissection, color illustration or model): oral, aboral (and why we use oral/aboral for these animals), mouth, tube feet, and madreporite, stomach, digestive glands, gonads (esp. on the model), and radial canals.
The characteristic of crayfish and clam gills that makes them similar to each other.