Download General Zoology Handout

General Zoology Handout
Lab 4
Protostome: Have determinate spiral cleavage, mouth derived from blastopore of gastrula
Lophotrochoan Worms: Possses either a trochophore larvae or a lophophore (ciliated organ
around mouth)
Exercise 9: Acoelomate animals (Pg. 135-147)
The term acoelomate refers to animals that have no true body cavity. There are three phyla that
fall into this classification; we will be looking at one of them in lab. The space between the body
wall and the digestive tract is not a cavity and the tissue type found there is referred to as
parenchyma. These organisms are the first that we encounter that are triploblastic. The
parenchyma is derived from the mesodermal layer during early development in these phyla. The
following terms are important when dealing with acoelomates: bilateral symmetry, organs,
cephalization, tissue-organ level of organization.
Phylum Platyhelminthes: flatworms, include free-living planarians as well as parasitic tapeworms
and flukes.
Class Turbellaria: mostly free-living with a ciliated epidermis *** Look at slides of the
planarian and sketch what you see (Figure 9-1 & 9-2).
Class Monogenea: larva is typically free-swimming and ciliated; adults covered with a
syncytial tegument without cilia; all parasitic; monoecious (hermaphroditic); posterior
attachment organ with hooks or clamps. Do not have.
Class Trematoda: adult body covered with syncytial tegument without cilia; oral and ventricle
suckers are typical (no hooks); parasitic; first host=mollusk, second host=vertebrate ***
Sketch the slides of Clonorchis sinensis (Fig. 9-3). Look at the demo slides of the life
cycle (Fig. 9-4).
Class Cestoda: tapeworms; adult body covered with syncytial tegument without cilia; scolex
with suckers or hooks for attachment; ribbon-like body usually divided into proglottids;
no digestive organs; parasitic on vertebrates *** Look at the array of Dipylidium canium.
Sketch what you see (Figure 9-6,9-7,9-8).
Exercise 10: Pseudocoelomate animals (Pg. 163 &164)
Pseudocoelomates are animal that do have a body cavity but the cavity itself is not entirely lined
with peritoneum. There are seven phyla that fall in this group and they are all said to be at the
organ-system level of organization. You will be responsible for characteristics of four of those
phyla. With the exception of the acanthocephalans, these organisms have a complete mouth-toanus digestive tract.
Phylum Rotifera: Rotifers are an extremely variable pseudocoelomate. Look at demo on side of
room.
Phylum Acanthocephala: do not have a complete mouth-to-anus digestive tract; spiny-headed
worms; dioecious; proboscis on the end has six rows of hooks to attach to the intestinal walls
of hosts; male is much smaller than the female. Look at preserved specimens on the side of
the room.
Exercise 12: Phylum Annelida
Annelids are “segmented worms”; typically elongated, wormlike animals, which are
circular in cross-section and have muscular body walls. They possess a coelomate body
plan. Their bodies show metamerism, or repeated body segments that are both internally
and externally similar. The body cavity in annelids is divided up into fluid filled parts,
making hydrostatic pressure useful in precise locomotion. They have a well-developed
circulatory system with pumping vessels, a neural system and a complete mouth-to-anus
digestive system. Therefore, annelids are classified as organ level of organization.
Class Polychaeta: Segmented inside and out; parapodia with many setae; no
clitellum; separate sexes; distinct head with eyes *** Observe the preserved
specimen of Nereis that is available in the lab. You are responsible for the following
external features of Nereis on page 189 of your manual: parapodia, setae,
peristomium, prostomium, jaw, anus, and cirri. Take the specimen out of the jar
to familiarize yourself with those features if you’d like. Observe the other specimens
in jars that belong to this class.
Class Oligochaeta: Body segmented inside and out; clitellum present; few setae; no
parapodia; head poorly developed; coelom spacious and usually divided by
intersegmental septa *** Look at the slide of the cross-section of an earthworm
comparing it to Figure 12-5 on page 195 of your manual. In addition, using Figure
12-3 page 193 of your manual as a reference, dissect out the internal structures of an
earthworm, familiarizing yourself with and labeling the following: mouth, pharynx,
brain, hearts, testes, esophagus, ovary, crop, gizzard, intestine, nephridia. Make
sure you know the difference is dioecism and monoecism.
Class Hirudinae: Leeches; many annuli; clitellum present; anterior and posterior
suckers; setae typically absent; parapodia absent; coelom closely packed with
connective tissue and muscle. *** Observe the preserved leeches. You are
responsible for the following external features on figure 12-7 page 200: oral
sucker, caudal sucker