Class Polyplacophora 1. Chiton for Dissection i.e. Katherina sp. External Anatomy 8 valves, girdle, mouth, foot, mantle cavity, ctenidia, anus Valves - distinguish head and tail valve (what features distinguish them? Insertion teeth, articulations, what distinguishes the tegmentum from articulamentum in valves), intermediate valves (dissect out and check for esthete channels) Processes check the chiton girdle for scale (papillae, granules, scale) and hair (setae, spicules) processes Internal dissection (cut from dorsal side after removing the valves) esophagus, stomach, gonad (can you distinguish sexes?), pericardial cavity 2. Various chitons for observation can you tell what environment these animals may live in? how may they adapt to their environment?
Class Gastropoda Subclass Prosobranchia (Eogastropoda) = shelled gastropods, mantle cavity in the anterior position and figure 8 nerve cords Order Archaeogastropoda Haliotis sp. abalone, 4-15 holes, oval, scalloping around edges Limpets true limpets are only marine, some produce home scars (why might that be advantageous?) Class Gastropoda Subclass Prosobranchia (Eogastropoda) Order Mesogastropoda (Pectinibranchia) no nacreous layer to the shell (mother-of-pearl layer), bipectinate gills Crepidula fornicata slipper shell, attached to stones, other shells and each other, sequential hermaphrodites, oldest animals at the bottom of a stack are females, youngest at the top are males, what about the animals somewhere in the middle? Strombus gigas queen crown conch, cut shell to observe periostracum and prismatic, technically no nacreous
Class Gastropoda Subclass Prosobranchia (Eogastropoda) Order Neogastropoda long incurrent siphon and associated siphonal structure (how do these animals feed?) Busycon whelks, marine gastropods, may be right or left handed (twisting of the shell), observe the large operculum (what might be the use of that), also see the whelk eggs Class Gastropoda Subclass Ophistobranchia have at least one pair of tentacles they cannot withdraw, rhinophores (detection of smell), many show shell reduction (slugs) Live sea slugs for observation, how do these animals eat? How do they move? Class Gastropoda Subclass Pulmonata Order Basommatophora eyes at the base of non-retractible tentacles Heliosoma sp. freshwater snail, bulbous, planispiral shell that may contain an air bubble Observe freshwater snails (live) for radula movement (what are these organisms doing with the radula?) Class Gastropoda Subclass Pulmonata Order Stylommatophora order of air breathing land snails or slugs Limax sp. terrestrial slug, notice absence of the shell (how may these organisms defend themselves from the onslaught of the environment? How do they avoid dessication?)
Helix sp. terrestrial snail, operculum lacking External anatomy mantle, foot, pneumostome (use?), anus, shell, tentacles, eyes, genital aperture Internal anatomy see model of dissected snail In some cases, it may be possible to remove the dead animal from its i shell using curved forceps. If this is not possible, slowly break the shell from the aperture backwards, following the whorls, until the animal can be removed from the shell intact. (It is important to retain the broken pieces of the shell for identification purposes). A pair of needle- nose pliers may be used depending on the size of the animal s shell. Uncoil snail and make an incision above the mantle skirt. Slowly uncoil the portion of the animal that was inside the shell to expose its contents. Make e an incision just above the mantle skirt. Be sure to make shallow incisions and angle the scissors upwards, and away from the internal organs. Cut as far along the skirt as possible. Cut along the length of the thin membrane. Peel back the membrane to expose the internal organs. Peel back the transparent membrane to expose the internal organs. Continue with the incision all the way to the end of the coiled regions of the animal (portion that was retained inside the shell). The animal may be inverted to accomplish this. Slowly tease the ovotestis and the albumen gland away from the digestive gland. Both organs can be carefully separated with a pair of tweezers. Once dislodged, both systems can be separated. Cut forward into the mantle skirt to expose the base e of the reproductive system. Rotate the animal unto the side (may have to hold in hands) and cut into the mantle skirt going forward, towards the head. Be sure to make the incision between the ocular tentacles. This cut will expose the basal region of the reproductive system. Detach the reproductive system. Gently separate the reproductive system from the digestive system. Make incisions but be careful to avoid cutting through the atrium. This incision will detach the entire reproductive system form the rest of the animal. Use an insect pin to gently unravel the vas deferens, bursa copulatrix, oviduct, flagellum, and penis by following the connection to each.
Class Bivalvia Subclass Lamellibranchia ctenidia longer and folded back to form two lamellae Order Anisomyaria one adductor muscle only Crassostrea sp. oyster, economical importance, shell thick, flattened and variable in shape, contains concentric ridges Aequipecten scallop, shells are convex, shells variable in color, life animals have distinct blue eyes lining the mantle Mytilus edulis blue mussel, shell inequilateral and roughly triangular, shell shapes may vary, smooth with concentric lines
Class Bivalvia Subclass Lamellibranchia Order Heterodonta marine bivalves, generally with two adductor muscles Mercenaria mercenaria quahog, very thick shell which is available for shell analysis Larval slides trochophore larva Mya arenaria steamer, softshell clam, long pronounced siphon which may never be completely withdrawn between the shells Live specimens for blood withdrawl and gill dissection Preserved specimens for dissection Geukensia dimissa ribbed mussel, with a ribbed shell and a narrow blunt pointed head, shells are olive brown Class Bivalvia Subclass Lamellibranchia Order Schizodonta teeth of the valves are large, amorphous and variable Representative freshwater bivalves and freshwater clam glochidia Order Adapedonta boring mussels
Ensis sp. razor clam Class Cephalopoda Subclass Nautiloidea Nautilus sp. internal chambers, siphuncle, sutures and septae, body of the animal only contained in the last chambers Subclass Coleoidea primarily soft-bodied cephalopods Order Teuthida semi-gelatinous body, body is long and tapered, tentacles (paired) and paired arms (4 pairs) Loligo sp. squid Specimen for dissection (also External anatomy tentacles, head, eyes, funnel (siphon), mantle, mantle-locking cartilage, fins (internal stiff pen), mouth with beak Internal anatomy organs of Verrill, cephalic retractor muscle, articulating ridge, ctenidia, inc sack, kidneys, branchial heart, caecum, gonad Injected squid anterior vena cava, posterior vena cava Order Sepiidae long, oval body, dorso-ventrally flattened, thick internal shell Order Octopoda short compact body with only 8 arms with suckers, funnel valve absent