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Biol 111 Lab 1: Evolution of Vertebrates 1

Biol 111 Comparative & Human Anatomy

Lab 1: Introduction & Evolution of Vertebrates Spring 2014

Philip J. Bergmann

Lab Objectives The laboratory portion of the course is designed to coincide as much as possible with the lecture.

It aims to give you a hands-on, practical, and interactive experience, allowing you to better learn

anatomy and to hone your dissecting skills. While the lecture emphasizes the evolution of

anatomy, the lab emphasizes the anatomy itself (but still in an evolutionary context). The

laboratory is an integral component of the course, needed to properly learn anatomy. The major

objectives of the lab are:

1. To learn the basic anatomy of vertebrates in general.

2. To appreciate how the various anatomical systems are functionally integrated with one

another.

3. To learn to do detailed, beautiful dissections.

4. To learn how to approach the dissection of anatomy so that you are able to study any part

of the anatomy of any vertebrate.

Lab Schedule The lab for Biol 111 is scheduled for three hours a week for 14 weeks. You will find that it is

often necessary to spend more time during the week than three hours doing the dissections and

studying the anatomy. To help you with this, there will be an open lab policy (see below) during

weekdays. The lab schedule is as follows:

Week of Topic January 14 Introduction, Evolution of Vertebrates: Protochordates & Agnathans

January 21 Cranial Osteology

January 28 Postcranial Osteology, Shark External Anatomy & Fin Musculature

February 4 Myology: Shark Demo & Cat 1

February 11 Myology: Cat 1

February 18 Myology: Cat 3, Review

February 25 Lab Exam 1

March 4-8 No lab Semester Break March 11 Shark Digestive, Respiratory & Urogenital Systems

March 18 Cat Digestive, Respiratory & Urogenital Systems

March 25 Shark Nervous System: Graded Dissection

April 1 Circulatory System: Shark 1

April 8 Circulatory System: Shark 2, Cat 1

April 15 Circulatory System: Cat 2

April 22 Lab Exam 2


Lab Components The lab will be evaluated based on several components, worth 50% of the course grade:

Lab Exam 1 120 points 12% of total course grade February 26, 28

Lab Exam 2 120 points 12% April 23, 25

Graded Dissection 100 points 10% March 26, 28

Lab Quizzes 60 points 6% Ongoing

Course Participation 100 points 10% Ongoing

Below is information about each component, also found in the course syllabus.

Laboratory Exams There will be two lab exams during the semester. These lab exams will test your knowledge of

material presented and available in lab. Because this is an anatomy lab, you will be expected to be

able to identify anatomical structures and to know their functions and relationships to other

structures. The lab exam format will consist of fill-in-the-blank questions, and some short answer

(couple of sentences) questions. The exams will be in the form of stations with demo material

about which you will be asked questions. The stations will be timed so that all students have a

chance to see all of the material, and time will be available to return to stations you want to revisit

at the end of each exam. Lab exams will not be cumulative. A term list will be provided with

each exam that lists all terms that students are responsible for in alphabetical order (not by lab).

Due to the nature of these exams, making up a missed exam is extremely difficult.

Graded Dissection An important skill gained during this course is the ability to dissect vertebrates. You will spend a

lot of time honing your dissection skills, and so it is only fair that part of the grade be determined

by how well you learn to dissect. Students will have one week to dissect the shark brain and

origins of the cranial nerves in late March and early April and will be graded on the quality of

their dissections. A good quality dissection is one that has all structures undamaged, clearly

visible and identifiable.

Lab Quizzes During some labs, you will be given short (5-10 minute) quizzes on material either covered during

the previous lab or during that weeks lab. The primary purpose of these quizzes is to give

students a gauge of how they are doing in the lab in terms of learning the material. There will be

six quizzes, three before each of the lab exams.

Course Participation Attending all labs is mandatory and contributes to the lab participation grade. This 10% of the

course is also based on participation, completion of dissections and worksheets, and a good

attitude during labs. At the beginning of each lab, students should show the TA their worksheet

from the previous lab to get a check mark. The TA will also lead a discussion of the previous

labs questions at the beginning of lab. It is expected that students take part in the discussion by

answering questions and contributing ideas. During the last lab before each lab exam, the

instructors will also note the degree of completeness of the dissection up to that point of the

course. This should be an easy 10% of the course, but really depends on you being engaged. Part

of this grade is also for participation during lecture.


Using the Lab Handouts There is a handout associated with each lab session, available on the course website as a PDF.

Each handout will help to guide you through each lab and is particularly important because it

contains information about the material you should learn for each lab. Before studying from the

purchased lab manual, refer to the lab handout to determine what you need to know. Each lab is

presented in the same format. The Lab Objectives is a short section outlining what you should be

doing and learning during each lab. The Material to Learn section contains information on

which aspects of the anatomy you need to learn and those that you do not, and this is summarized

as concisely as possible with a listing of figures and tables to learn and omit, all referenced to the

lab manual, The Dissection of Vertebrates by De Iuliis and Pulera. This section also contains a list

of terms that you need to learn. This is the definitive list that you can use as a study guide for each

lab. There are a lot of terms and this list should help you manage learning them. Note that there

are terms that appear in the lab manual figures that you do not need to know. A useful strategy is

to go through the term list for each lab and put a small "x" beside the terms in the figures of the lab

manual that you do not need to know. The Background & Instructions section tells you what

you should be doing during each lab, and includes specific directions for doing the dissection for

each lab. These instructions are crucial to getting started and completing each lab efficiently.

Your TA and Dr. Bergmann will be available to further help in case of uncertainty ask them

many questions. This section also contains key background information to learn. Finally, it

contains questions for you to complete during and after the lab. These questions appear in bold

and italics. Some time will be spent at the beginning of each lab discussing questions from the

previous lab, so come prepared to participate in the discussion (participation points!). These

questions will help put the anatomical material into a broader context, relate it to the lecture, and

prepare you for exams.

You will quickly realize that there is a lot of text to go through in the lab manual and you are

expected to read each lab before coming to lab. Do not wait until lab to read the lab handouts and

manual because there will not be enough time to complete the dissections. Please come prepared

to each lab: read the entire lab before coming, and bring a print out of the lab handout and your lab

manual. It is a good idea to bring past lab handouts as well, so that you can review material from

previous weeks.

Supplies Gloves, lab aprons, specimens and dissecting tools are available in the lab. If you wish, you may

purchase your own dissecting kit this is the best way to ensure that your tools are in good

condition. Bringing the lab manual and lab handout to each lab is critical to doing the lab.

Specimen Preservation and Safety You will be handling preserved lamprey, shark and cat specimens extensively during each lab of

the course. These specimens are fixed in 10% formaldehyde solution, called formalin, and stored

in a less toxic holding solution. Formaldehyde is a carcinogen and quite pungent. It is the major

health hazard in the lab. To mediate this hazard, when not in use, specimens are stored in a sealed

refrigerator. The lab is also equipped with ventilation fans that easily maintain fumes at non-toxic

levels. Despite these precautions, the fumes can be quite strong and protecting yourself is

important:

1. Wear gloves whenever handling specimens.

2. Do not eat or drink in the lab (this is prohibited).

3. Step out of the lab for a couple minutes a few times a lab session to get some fresh air.


4. If you feel ill from the fumes, excuse yourself and step out of the lab.

5. If you are or may be pregnant, inform Dr. Bergmann and consult your physician.

Another hazard in the lab is the use of sharp implements, including scalpels and scissors. Be

careful when dissecting with these instruments. Always point the sharp and pointy ends away

from yourself and others. Always report any accidents to the TA or Dr. Bergmann immediately.

A first aid kit is available if needed.

Open Lab Policy The instructors make every effort to open the lab outside of scheduled class time for students to

facilitate completion of dissections, review and learning of the material, and studying for exams.

Open lab must be requested by students, and agreed to by the TA or Dr. Bergmann. Students

should arrange for open lab preferably at least 24 hours in advance. While the instructors are

willing to open labs even on short notice, they also have other responsibilities and meeting or

other plans may prevent them from being able to open lab if it is requested at the last moment.

Lab can be opened during most times during the week, including the weekend. Weekend times

must be arranged by the end of Thursday. There are a few times when lab will not be opened.

Lab will not be open during the day prior to a lab exam, as this time is used to set up the exam.

Lab will also be closed during the 45 minutes prior to the beginning of labs (so 12:40-1:25 on

Tuesday and Thursday). Finally, open lab may also be unavailable if another class is using the lab

space (such restriction is usually minimal).

Other Lab Rules In addition to the safety rules discussed earlier, please follow these important rules:

1. Attend all labs and show up on time. TAs and Dr. Bergmann will have important

information for you at the beginning of each lab session.

2. Keep the lab tidy. When you finish dissecting, put away your specimen, dispose of any

biological waste in the appropriate place, wash and put away your dissecting tray and

tools, and wipe down your lab bench. Leave the lab as clean or cleaner when you are done

than when you started.

3. Be courteous and helpful to other students and instructors in the lab.

4. Treat the specimens with respect. Keep in mind that all of the animals that you are

dissecting were once alive. Your opportunity to dissect them to learn anatomy is a

privilege, so treat them with appreciation and respect. This means no playing with the

specimens, scaring other students with the specimens, or making distasteful jokes about the

specimens. Other students may have fishes or cats as pets and may be offended by such

behavior.

5. Do not remove specimens from the lab.

6. Do not damage or monopolize demonstration material it should be available to all

students.


Evolution of Vertebrates: Protochordates & Agnathans

Lab Objectives 1. To learn the anatomical planes and directions so that you can read and talk anatomy.

2. To learn the 5 key chordate characteristics (what makes a chordate a chordate).

3. To be able to identify the chordate characteristics in the Urochordata, Cephalochodata, and

lamprey.

4. To learn the difference between chordates and vertebrates.

5. To learn the anatomy of the lamprey, a primitive vertebrate, establishing a baseline for

comparison to the shark and the cat.

Material to Learn 1. Anatomical planes and directions:

Figures 1 & 2

2. Chordate phylogeny and key characteristics:

Figure 1.1 (Figure 1.2 is helpful for material covered in lecture)

Text in sections on Vertebrate Relatives & Craniates and Vertebrates (pp. 4-8)

4. The chordate characteristics in Urochordates, Amphioxus and larval lamprey (see below)

5. Lamprey anatomy, Chapter 2:

Know: Arcualia only in Fig. 2.1

Know: Fig. 2.2, 2.3, 2.4, 2.7, 2.8, 2.9

OMIT: Fig. 2.5, 2.6. Blood vessels, except dorsal aorta.

Term List Intoduction

Anterior

Posterior

Dorsal

Ventral

Medial

Lateral

Proximal

Distal

Sagittal

Transverse

Frontal

Deep

Superficial

Combined terms (e.g.,

posteroventral,

anterodorsal, anterolateral,

posteromedial)

Chapter 1 & Related

Hemichordata

Urochordata

Chordata

Cephalochordata

Craniata

Vertebrata

Myxinoidea

Petromyzontoidea

Ammocoetes larva

Gnathostomata

Chondrichthyes

Osteoichthyes

Sarcopterygii

Tetrapoda

Pharyngeal slits

Endostyle

Dorsal, hollow nerve cord

Notochord

Post-anal tail

Gill slits

Thyroid gland

Atriopore

Adhesive papilla

Sessile

Gill filaments

Subpharyngeal gland

Muscle

Chapter 2

Anterior dorsal fin

Anus

Arcualia

Brain

Caudal fin

Cloaca

Dorsal aorta

External Pharyngeal Slits

Eye

Horny Teeth

Heart

Intestine

Lateral line pores

Liver

Mouth

Myomeres

Myoseta


Naris

Notochord

Olfactory sac

Oral funnel

Ovary

Pharynx

Pineal eye complex

Posterior dorsal fin

Spinal cord

Tail

Tongue

Trunk

Urogenital papilla

Background & Instructions You will not be dissecting during todays lab, although you will get plenty of opportunity to

dissect later during this course. Instead, there is demonstration material available for examination

and study. On demonstration there is a series of microscope slides, and a number of specimens of

the lamprey. The microscope slides are all of basal chordates: the Urochordata (sea squirts),

Cephalochordata (Amphioxus), and the Ammocoetes larva (larval lamprey). Also, answer the

questions throughout this lab after you have read the material and as you examine the demo

material.

All of the animals that you see today are chordates, and so they all have five key chordate

characteristics at some point in their life cycles. Chordates are characterized by having

pharyngeal slits, a dorsal hollow nerve cord, a notochord, an endostyle, and a post-anal tail.

Throughout today's lab keep these characteristics in your mind and look for them in all of the

specimens that you examine.

Pharyngeal slits - are openings that evolved in the pharynx of chordates. The pharynx is

the anterior end of the gut, immediately posterior to the mouth. In vertebrates, the

pharyngeal slits become gill slits. In other forms, the slits are used for filter feeding,

allowing water to pass through them, but being too narrow to let food through.

Dorsal hollow nerve cord - is also called the spinal cord and, unsurprisingly, fills a

nervous function, connecting the brain with the rest of the nervous system.

Notochord - is a hydrostatic organ that acts as an endoskeleton it maintains the elongate

shape of the animal, preventing the body from collapsing on itself. Generally, the

notochord is dorsal in position and runs from anterior to posterior. It lies immediately

ventral to the spinal cord.

Endostyle - In basal chordates, the endostyle secretes mucous that is used to trap food

particles. It is also involved in iodine metabolism, and is homologous to the thyroid gland

of vertebrates. Typically, it is positioned ventral to the pharynx.

Post-anal tail - is a muscular projection posterior to the anus. It is typically used in

locomotion. Although some chordates (like humans) have lost the tail secondarily, it is

present in most species.


1. Amphioxus whole mount microscope slide and whole specimen Amphioxus is a cephalochordate. Although it is more closely related to craniates than the

Urochordata, we mention it first because it is a good example of a general chordate body plan,

and structures are relatively easy to find on it. Examine the slide under a dissecting microscope.

The slide is quite thick, so you will have to focus up and down through the animal to get a view of

all of the structures. Also look at the whole specimens these are helpful because you can see

what the actual animal looks like. Identify the five chordates characteristics:

Pharyngeal slits - Look for the pharynx at the anterior end of the animal. The slits run

from anterodorsal to posteroventral. During filter feeding, water enters through the mouth,

passes through the pharyngeal slits, and exits through the atriopore.

Dorsal hollow nerve cord This is a dark pink stripe that runs anterior to posterior along

the dorsal side of the animal.

Notochord This is a dark stripe that often stains a more orange color than the nerve cord.

It also runs along the dorsal side of the animal, located immediately ventral to the nerve

cord. It begins anterior to the nerve cord.

Endostyle The endostyle is a structure that is difficult to see in the whole mount. It runs

longitudinally along the ventral edge of the pharynx. In the whole mount, it may appear as

a darker pink stripe.

Post-anal tail Locate the anus, which is posterior to the atriopore and ventral on the

animal. The part of the animal posterior to this is the post-anal tail.

In examining the whole mount, but also the whole animal, note the myomeres, which are

segmental muscles running more or less transversely along the animal. They form a fine

chevron pattern.

Use the remainder of this page to draw the amphioxus whole mount. Label all the structures

that you identify.


What are five features that all chordates have?

Do you have all of these five features? Which ones do you lack?

What happened? Why are humans still considered chordates?

2. Urochordata larva and adult The urochordates, or sea squirts, are a clade of chordates, meaning that they have all five chordate

characteristics. However, unlike the other animals on display, the urochordate larva differs

tremendously from the adult. The larva does not feed and is motile, dispersing after hatching and

finding an appropriate place to settle. Once it settles, it attaches to the substrate using its adhesive

papillae, and metamorphoses into a sessile, feeding adult. Due to these differences, neither the

larva nor the adult have all five chordate characteristics, but together they have all of them.

Examine the slides of both larva and adult and consider which chordate characteristics you

see in each.

Use the remainder of this page to draw the larval and adult sea squirt. Label the structures that

you identify.


Which key chordate characteristics does the urochordate larva have? How about the adult?

3. Ammocoete larva of the lamprey, whole mount and composite cross section slides The larval lamprey looks quite different from the adult, but quite similar to amphioxus. The

lamprey is a chordate. It is also a vertebrate, containing small vertebral rudiments called arcualia

around its notochord when adult (see below). It is a good example of how an embryonic animal

can have a relatively generalized morphology and subsequently specialize for its adult life style.

The ammocoete is a small filter feeder, while the adult lamprey is parasitic, opening wounds on

fishes with its teeth and feeding on their bodily fluids.

Use a dissecting scope to examine the whole mount of the ammocoete larva. Note how it looks

very similar to amphioxus. Try to identify the five key chordate characteristics - they should be in

the same place as you saw in amphioxus.

Use a compound or dissecting microscope to examine the cross sections of the ammocoete larva.

Identify the dorsal hollow nerve cord (a dorsal structure, now cut in cross section), and the

notochord ventral to it. Identify a cross section through the pharyngeal area by noticing the

feathery gill filaments that project laterally from the wall of the pharynx. The pharynx is the

central space through which water and food pass. Ventral to the pharynx is a bilaterally

symmetrical lobed organ called the subpharyngeal gland. This is a version of the endostyle.

Switch to a posterior cross section through the ammocoete. Notice the nerve cord and notochord,

which project all the way to the posterior end of the tail. A dorsal fin appears as a thin dorsal

projection from the tail. The caudal fin is the ventral projection. Also notice the masses of

muscle in the tail, which are used to generate forces for propulsion through the water.

Use the remainder of this page to draw and label the ammocoete cross sections that you look at.


What are two differences between that amphioxus and ammocoete whole mounts that you can

use to distinguish these animals?

4. Adult Lamprey specimens A number of adult lamprey specimens are available on demonstration. These are pre-dissected for

you, so you do not need any dissecting tools other than a metal probe to use to point to structures.

Wear gloves to handle these specimens, as they have been preserved in formalin. As you examine

the adult lamprey, see if you can find all of the key chordate characteristics and consider how the

animal is specialized for its lifestyle. The lamprey serves two important purposes in this lab.

First, it shows how the key chordate characteristics appear in a large, non-microsopic animal.

Second, it gives you an anatomical baseline of what a basal vertebrate looks like. It will serve as a

good foundation to build knowledge upon as you dissect the shark and cat in upcoming labs.

Examine the following:

Whole lamprey specimen - Examine the external morphology, identifying the structures

shown in Figures 2.2, 2.3 and the lower right of 2.4.

Cross sectioned lamprey specimen - Identify the structures shown in Figures 2.7 & 2.9 that

you are responsible for (see term list).

Mid-sagittally sectioned lamprey specimen - Identify the structures shown in Figure 2.8.

Although all views are important, this one shows the most. Again, consider only the

structures that you are responsible for (you can omit many of the muscles, some cartilages,

and the blood vessels, but know what the heart is).

Describe the life style of the larval and adult lamprey. How do they differ?

What are at least two specializations that the adult lamprey has for its lifestyle?

How has the function of the pharyngeal structures changed from Amphioxus to a lamprey?

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