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Biology Inquiry and Outreach with Boston University Graduate Students (BIOBUGS) presents: Comparative Vertebrate Anatomy
In the same way that a dead body can provide forensic detectives with the clues to solve a murder case, the bodies of animals can tell us a lot about their ecology and evolution. In this lab we will study the internal anatomy of the five classes of the vertebrates (fish, amphibian, reptile, bird, and mammal) through hands-on examination of dissected whole specimens as well as prepared skeletons and skins. We will ask students to formulate hypotheses about the ecology of each dissected species based on their observations of the similarities and differences between each specimen. Students will also learn how to use their morphological observations to construct a phylogenetic hypothesis of the evolutionary history of each vertebrate class.
Massachusetts Educational Standards addressed by this lab:
Scientific Inquiry Skill Standards: SIS1 – Make observations, raise questions, formulate hypotheses SIS3 – Analyze and interpret results of scientific investigations
Biology Standards:
- Anatomy and Physiology
- Evolution and Biodiversity
- Ecology
Lesson Topic: Comparative Vertebrate Anatomy
Materials (for 24 students) We will need twice this much for two sections.
Powerpoint projector Computer Chalk, Whiteboard Pens, or Butcher Paper and Pens Student worksheet Disposal for dissections Magnifying Glasses Rulers 24 pairs of gloves 24 pairs of protective glasses
Part 1: Skeletal Anatomy (Bio Museum)
Station 1: Skulls from Coyote, Bear and Deer. No labels.
Station 2: Skulls from Bat, Shrew, and two dissection microscopes with light.
Station 3: Skeletons of Pigeon, Bat
Station 4: Skeletons of Salamander, Pigeon, Frog
Station 5: Skeletons of Turtle, Perch
Station 6: Skeleton of Cat
Part 2: Internal Anatomy (Carolina Biological Supplies)
Disposable Gloves! Dissecting tools for instructors only (1 of each species) Magnifying glasses
Station 1: Cat (to be dissected in demo)
Station 2: Turtle (pre-dissected)
Station 3: Pigeon (pre-dissected)
Station 4: Salamander (pre-dissected)
Station 5: Perch (pre-dissected)
Station 6: Dogfish (pre-dissected
Station 4: Fusion Power Students will be asked to compare the skeletons of a salamander, a frog and a pigeon. They will be told that the well-developed and flat urostyle in the frog is a result of the fusion of many bones in the pelvic girdle (the hip bones), and the well developed and flat keel and furcula (wishbone) of the pigeon come from the fusion of many bones in the pectoral girdle (the shoulder and chest bones). They will be able to see that these bones are not fused in the salamander. They will be asked to think of possible reasons why both the urostyle and keel are so flat (muscle attachment).
Students should also note the following characters in the salamander: Presence/absence of calcified bone Presence/absence of vertebrae Presence/absence dorsal process on vertebrae Presence/absence of 4 walking limbs Presence/absence of beak Presence/absence of shell
Station 5: Pet Cemetery: Turtle and Fish Students will have a chance to examine the skeletons of a turtle and a fish to gather further characters for their phylogeny. Characters they should get at this station for each skeleton: Presence/absence of calcified bone Presence/absence of vertebrae Presence/absence dorsal process on vertebrae Presence/absence of 4 walking limbs Presence/absence of beak Presence/absence of shell
Station 6: Cat Skeleton Students will have a chance to examine the skeletons of a cat to gather further characters for their phylogeny. Characters they should get at this station for each skeleton: Presence/absence of calcified bone Presence/absence of vertebrae Presence/absence dorsal process on vertebrae Presence/absence of 4 walking limbs Presence/absence of beak Presence/absence of shell
Closing Discussion: We will need to have everyone sit down and go through the worksheet, and try to get the group to come up with some answers through guided discussion, either using the board, or a projector and computer. Important concepts to teach here are how skull adaptations reflect trophic level and lifestyle in mammals (from Stations 1 and 2), and the concept of homology and the difference between homology and homoplasy (Stations 3 and 4). Discussion of the phylogeny characters can be held off until part 3.
Part 2: Internal Anatomy (1.5 hours) Introductory Lecture and Dissection Demo: See Comparative Anatomy Instructor for proper cat dissection and lecture. Here we can unite the concepts of homology and adaptation and have the students consider how homologous structures differ between animals, based on their habitat and life history. This should pretty much lead into the demo of the cat dissection, during which the instructor should refresh the students on the basic functions of the homologous structures listed below.
The students should keep track of the relative size and shape of the following homologous structures: Heart, Lungs/Swim Bladder, Large Intestine, Kidney, Liver, Skin Covering. Each member of each group should choose between these structures as the one that they want to specialize in, and be in charge of drawing this structure in each of the animals as the group moves around the stations.
Activities at each station will be the same. Students should make observations on each of the structures above in their chart. They should then draw their assigned structure in space provided on the worksheet. Anyone working on skin should be encouraged to draw a single unit of the skin covering at magnification. Finally, they should collect the following characters:
Relative size of large intestine Presence/Absence of Diaphragm Skin Covering
Station 1: Cat (8 minutes)
Station 2: Turtle (8 minutes)
Station 3: Pigeon (8 minutes)
Station 4: Salamander (8 minutes)
Station 5: Perch (8 minutes)
Station 6: Dogfish (8 minutes)
Closing Discussion: Each group should briefly (in a minute or less) present their findings about the trait they investigated. They should point out trends or major differences that they noticed. We can then have a brief guided discussion about why differences in these traits might help each organisms adapt to their habitat.
