General Zoology Handout
Lab 9
Phylum Hemichordata: Have gill slits and stomochord. Aquatic. Acorn worms, wormlike,
head, collar, trunk
Exercise 17: Phylum Chordata
Most chordates are vertebrates, although there are some invertebrates in the group. All
animals that belong to the phylum must show the following four characteristics at some
point in their life history: 1. notochord, 2. pharyngeal gill slits, 3. dorsal tubular
nerve cord and 4. postanal tail.
Group Protochordata: chordates with no cranium or vertebral column
Subphylum Urochordata: tunicates; marine; only larval forms have all characteristics;
adults sessile, without dorsal nerve cord or notochord *** Look at larva on slide and
note the 4 major chordate characters Figure 17-4. ***Look at the preserved sea squirts,
and know the following: tunic and siphons Figure 17-3
Subphylum Cephalochordata: lancet; notochord and nerve cord present throughout life
*** Look at the preserved amphioxus, you may take them out of the jar if you wish.
Also, be sure to look at all of the amphioxus slides, Figure 17-6. Label the following:
rostrum, oral hood with tentacles, wheel organ, gill slits and bars, notochord,
dorsal nerve cord, intestine, myotome, caudal fin.
Exercise 18: The fishes: lampreys, sharks and bony fishes
Subphylum Vertebrata (Craniata): enlarged brain enclosed in cranium; nerve cord
surrounded by bony or cartilaginous vertebrae; notochord in all embryonic stages
Superclass Agnatha: no jaws or ventral fins; notochord persistent
Class Petromyzontida: lamprey; most are anadromous *** Look at the preserved
specimen of a lamprey
Class Myxini: hagfishes; *** Look at the preserved specimen of a hagfish
Superclass Gnathostomata: jaws present; usually paired limbs; notochord persistent or
replaced by vertebral centra
Class Chondrichthyes: sharks, skates, rays and chimaeras *** Look at the preserved
shark. You are responsible for the external features of the shark on page 283 (Fig.
18-4). Sketch and label them.
Classes Actinopterygii and Sarcopterygii: these classes were formerly lumped
together; all bony fishes *** Look at the preserved specimens, skeleton, and
dissected specimen, and note the wide variety. Know (i.e. sketch and label) the
external features of a fish on page 288 (Fig. 18-9), and the internal features on page
291 (Fig. 18-12). Label the following: Heart, Liver, Operculum, Gills, Swim
Bladder, Stomach, Intestine, Spleen, Cloaca, and Gonad. Be sure to recognize
how the fins attach to the main body skeleton. This will become important as we
trace the evolution of appendages in the vertebrates.
General Zoology Handout
Lab 9
Exercise 19: Class Amphibia
This class includes frogs, toads and salamanders.
Order Gymnophiona: Caecilians, tropical legless (apoda)
Order Anura: Frogs and Toads
Order Caudata: Salamanders
You are responsible for the information on page 299 and 303-316. *** Look at the
preserved frogs and salamanders. Try to identify the features covered on the right
side of pg. 300 under “external structure”.
Look at the frog skeleton. Frogs and toads differ primarily from salamanders in their
ability to jump. They are able to do this because of specialized adaptations within
their skeleton. Sketch and label the back end of the skeleton, noting the following:
sacral vertebra, urostyle, ilia, ischium, femur, tibiofibula, (pg. 305 Fig. 19-3).
Finally, with your partner, obtain a frog for dissection. Use pg. 310-315 (fig 19-6 10). Read the section before making any incisions. If you are unsure of where to
start cutting, please ask for assistance. You need to identify the following: internal
nares, maxillary teeth, glottis, tongue, tympanic membrane, esophagus, heart
(ventricle), conus arteriosus, liver, gallbladder, stomach, small intestine, spleen,
large intestine, lungs, kidney, bladder, cloaca, fat body. You should also be able
to tell whether your frog is a male or female according to whether or not it has testis
or ovaries, and the corresponding sex organs. Sketch and label these in your
notebook.
Exercise 20: Class “Reptilia”
This former class included lizards, snakes, crocodilians and turtles. Below is the
updated taxonomy that we will follow in this lab.
Class Reptilia
Order Squamta: Lizards, Snakes, and Amphisbaens
Order Rynocephalian: Tuataras
Class Eusuchia: Aligators and Crocodiles
Class Chelonia: Turtles (know the Carapace and Plastron)
You are responsible for pages 321-326. Pay particular attention to the changes that
had to be made in class reptilia before they could be truly terrestrial. Know the
difference between the diapsid and the anapsid lineages and the importance of the
amniotic egg. *** Sketch at least one snake, lizard, turtle, and alligator using the
specimens available.