General Zoology Handout
Lab 6& 7
Bilateral/Protostomes
Ecdyszoans- shed their cuticle
Exercise 10: Pseudocoelomate animals (Pg. 156-164)
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-to-anus digestive tract.
Phylum Nematoda : found worldwide in terrestrial, freshwater, marine and parasitic forms; covered with a
flexible, non-living cuticle; circular muscles are lacking in the body wall *** Look at the slides of
Trichinella spiralis (Fig. 10-5) and Ascaris lumbricoides (Fig. 10-1, 10-2, and preserved specimens). Be
able to sex Ascaris. You will be expected to be able to identify these nematodes on your exam so pay close
attention to various examples in the lab and in your manual. Look at various demos on the side of the room.
Make sketches in lab to help you remember the differences between the species for later use in studying!
Phylum Nematomorpha: horsehair worms; long-cylindrical bodies; often found in puddles, ponds or watering
streams. Look at preserved specimens on the side of the room.
Exercise 13: Phylum Arthropoda, Subphylum Chelicerata (203-209)
Arthropoda is a huge phylum with over one million described species! Arthropods have jointed appendages
and tagmata (compare tagmata in arthropods to metamerism in annelids), which are segments that have fused
and are specialized to perform certain functions. This is the first phylum where we see striated muscle for rapid
movement. They also have an exoskeleton made of chitin used for support and protection. Gills and tracheal
system are used for gas exchange. The coelom is greatly reduced and the hemocoel is filled with hemolymph,
which flows around the arthropod’s open circulatory system.
Subphylum Chelicerata: First pair of appendages modified to form chelicerae; four pairs of legs; no antennae;
no mandibles; cephalothorax and abdomen usually unsegmented
Class Merostomata: aquatic; example horseshoe crab *** Look at the preserved specimens of horseshoe
crabs. You are responsible for knowing the following external features in your manual on page 205:
carapace, compound eye, simple eye, hinge, opisthosoma, telson, pedipalp, mouth, chelicera, book
gills, walking legs, anus,. Sketch and label these in your lab book.
Class Pycnogonida: Sea spiders, long thin bodies, four pairs of long walking legs.
Class Arachnida: Spiders and scorpions; head with paired chelicerae and pedipalps; four pairs of legs;
abdomen segmented or unsegmented; with or without appendages; respiration by gills, trachea, or book lungs
*** Look at the spiders, scorpion, ticks and mites (you may need a microscope for the ticks and mites). You
are responsible for the following external features of the spider on page 208: pedipalp, chelicerae, fang,
walking legs, cephalothorax, abdomen. Orders: Aranea-Spiders, Acarinae- Mites and Ticks, ScorpionesScorpions, Opilones- Harvestmen
Exercise 14: Phylum Arthropoda, Subphylum Crustacea (Pg. 211-220)
Subphylum Crustacea: have mandibles instead of chelicerae; two pairs of antennae and two pairs of maxillae
on the head; gill-breathing arthropods
Class Malacostraca: *** Look at a crayfish from the jar of preserved specimens. You are responsible for the
following external features (figure 14-1): cephalothorax, antennae, cheliped, rostrum, eye, antennules,
carapace, 5 walking legs, abdomen, telson, uropod, mouth, swimmerets, sternum, tergum, anus.
Sketch and label these. Cut the crayfish in half (mid sagittal section). Using figure 14-4A, indentify the
following structures: stomach, gills, heart, digestive gland, intestine, gonad (testis/ovary), abdominal
flexor muscle. Additionally look at the preserved specimens of other species.
Class Branchiopoda: 11 pairs of appendages used for locomotion, respiration and egg carrying; swim ventral
side up *** Look at the slide of Daphnia, Fig 14-5.
Class Maxillopoda:
Subclass Copepoda: Median eye and long antennae *** Look at the slide of Cyclops, Fig 14-5.
Subclass Cirripedia: barnacles; enclosed in a calcareous shell; all marine *** Look at the barnacles, Fig
14-5.
Subclass Ostracoda: Transparent bivalve carapace, 7 pairs of appendages, large antennules &
Antennae.***Look at slide of Cypris, Fig 14-5.
Exercise 15: The uniramia arthropods: myriapods and insects (Pg. 225-232)
The uniramia arthropods are centipedes, millipedes and insects. They have mandibles, spiracles, labrum, only
one pair of antennae, only uniramous appendages and breathe through a trachea. Remember, all of these
animals are still in the phylum Arthropoda.
Exercise 15A:
Subphylum Myriapoda: these organisms have two tagmata: head and trunk; trunk bears appendages on all but
last segment
Class Chilopoda: centipedes; active predators that live in moist places; some with ocelli, some with eyes
***, all have one pair of legs per segment.
Class Diplopoda: millipedes; herbivorous animals found in damp places; have diplosegments bearing
two pairs of legs each *** Look at the preserved specimens of millipedes in the front of the room.
Exercise 15B:
Subphlum Hexapoda:
Class Insecta: there are nearly one million described insect species, more than all other animals
combined! They have three pairs of walking legs; one pair of antennae; body typically divided into head,
thorax and abdomen; most have one or two pairs of wings; often have specialized sense organs *** Look at the
preserved insects at the front of the room, notice the diversity you see in only the few that are provided in the
lab. Next, get a preserved specimen of a grasshopper and become familiar with the external structures (Fig 153&4) using the manual as a guide. You are responsible for the external structures section on pages 228 and 229
of your lab manual. Sketch and label these. Cut the grasshopper in half (mid sagittal section). Using the figure
below identify as many internal structures as possible.