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LAB 9: ANIMAL DIVERSITY, FORM AND FUNCTION

(Online Lab)

READING: Please read chapter 17 in your text.

INTRODUCTION: The evolution of animal life (Kingdom Animalia) began about 700 million years

ago, in the sea, and today exhibits a diversity of forms. Before we begin our survey of animal phyla in

this lab, we should review some basic terminology. There are three types of body symmetry in

animals: (1) asymmetrical, meaning there is no plane of body symmetry; (2) radial, meaning the

body parts radiate from the center; and (3) bilateral, meaning the organism has a left and right side,

in addition to an anterior and posterior end. A coelom is a body cavity, a fluid-filled space located

between the digestive tract and the outer body wall. A true body cavity is completely lined by

mesoderm tissue, the “middle” layer of embryonic tissue. Animals may be acoelomate (lacking a

body cavity), pseudocoelomate (having a body cavity only partially lined by mesoderm), or

coelomate (having a true body cavity lined by mesoderm).

Modern day sponges (Phylum Porifera) represent the descendants of the most ancient animals.

Animals in this phylum are asymmetrical and lack true tissues. As new groups of animals evolved,

different forms of body symmetry arose, true tissues (e.g. skin, muscle, and nerves) formed, body

cavities evolved to cushion internal organs, and nervous and digestive systems became more

complex. A jellyfish (Phylum Cnidaria) is a relatively simple animal, with radial symmetry and a

gastrovascular cavity (a digestive compartment with a single opening serving as both mouth and

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anus). Bilateral symmetry arose later, with the flatworms (Phylum Platyhelminthes). Later still, a

primitive coelom and a complete digestive tract appeared in the mollusks (Phylum Mollusca) and

roundworms (Phylum Nematoda). Animal bodies eventually became segmented, as seen in Phylum

Annelida, which includes the familiar earthworm. Annelid body segments are relatively simple and all

very similar to each other. Animal body segments eventually became fused into fewer, but more

specialized, segments, as seen in the Phylum Arthropoda. Arthropods comprise approximately 2/3

of all species on the planet and include the familiar Class Insecta (arthropods with three-part bodies

and three pairs of walking legs, such as butterflies and beetles) and Class Chelicerata (arthropods

with two-part bodies and four pairs of walking legs, like spiders and ticks). Arthropod success on land

depended in large part on their tough, water-proof exoskeletons. Invertebrates, like the ones

mentioned here, dominated life on earth until the Silurian Period (about 439 million years ago). The

first vertebrates (Phylum Chordata, Subphylum Vertebrata) were small, fish-like organisms. Fish

diversified in the oceans, giving rise to Class Myxini and Class Cephalaspidomorphi (jawless

fishes), Class Chondrichthyes (sharks and rays), and Class Osteichthyes (bony fishes). Bony

fishes gave rise to the first land vertebrates, the amphibians (Class Amphibia) with their moist skins

and gelatinous eggs. Reptiles and birds (Class Reptilomorpha, formerly Reptilia and Aves,

respectively) later arose, with their watertight scales (modified as feathers in birds) and amniotic

eggs, giving them an advantage in terrestrial habitats. Later still, mammals (Class Mammalia)

evolved from reptilian ancestors, developing fur from ancestral scales.

LABORATORY OBJECTIVES: The goals of this lab activity are for you to learn to identify members

of the major animal Phyla and Classes, and to become familiar with the characteristics of each.

Further, you will dissect two invertebrate animals, comparing and contrasting their internal and

external anatomies.

A. Animal Diversity

We will begin this lab by exploring animal diversity in the Kingdom Animalia. On page 3, you will find

a table where you will characterize 4 different organisms that belong to 4 different phyla.

For each animal, research the animal and describe the characteristics that are diagnostic of the

Phylum and/or Class (i.e. body symmetry, complete or incomplete digestive systems, body

segmentation, presence of special structures such as shells, jointed appendages, etc.).

One of your specimens must be a mollusc, one must be an arthropod, and one must be a chordate;

the remaining specimen may be from any other Phylum. For molluscs, arthropods, and chordates,

you must also classify the organism to Class. The crown jellyfish has been completed as an

example. (But this does not count as one of your 4!)

If you are unsure of where to start in choosing organisms, several example organisms are listed on

pages 4-7. You are welcome to research these, or you may select others that interest you. Just be

sure you look at at least one organism that is a mollusc, arthropod, and chordate!

It will be in your best interest to take the time fill out this table as you research organisms. You will

need this information on the quiz, and you will not have time to look up this information when you are

in the middle of a timed quiz!

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Organism Phylum Class Body

Symmetry

Acoelomate, pseudocoelomate,

coelomate?

Complete or Incomplete Digestive

tract?

Body Segmentation

Special Characteristics

Crown Jellyfish

Cnidaria Scyphozoa Radial Acoelomate Incomplete Absent -Bioluminescent -They use the light produced to distract or mislead predators

1. Mollusca

2. Arthropoda

3. Chordata

4.

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Crown Jellyfish Cuttlefish

Blue Ringed Octopus

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Indian Red Scorpion Tapeworm

Earthworm Dog (Canis familiaris)

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Common Snapping Turtle Yellow Tube Sponge

Goliath Birdeater Tarantula Eastern Lubber Grasshopper

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Horseshoe Crab Pacific Oyster

African Bush Elephant Sea Cucumber

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B. Comparative Anatomy

Now that you have taken some time to explore diversity in all of Kingdom Animalia, we will next take a

closer look at the anatomy of two invertebrates and make comparisons between them. View the

following videos for an earthworm and a lubber grasshopper dissection. As you view the videos, label

the parts of earthworm and grasshopper. A word bank of structures you should identify is included

with each set of images.

Earthworm Dissection

https://www.youtube.com/watch?v=u9HHS1uPFSo

1. _________________________

2. _________________________

3. _________________________

4. _________________________

5. _________________________

6. _________________________

7. _________________________

8. _________________________

9. _________________________

10. ________________________

11. ________________________

Clitellum Seminal Receptacle Gizzard Aortic Arches (Hearts)

Dorsal Blood Vessel Pharynx Crop

Seminal Vesicle Mouth Metanephridium

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Grasshopper Dissection

https://www.youtube.com/watch?v=P_jEmEfocdk&t=2s

*Only need to watch through 11:20 to get through all anatomy you will need to know*

1. _______________________

2. _______________________

3. _______________________

4. _______________________

5. _______________________

6.________________________

7. _______________________

8. _______________________

9. _______________________

10. ______________________

11. ______________________

12. ______________________

13. ______________________

14. ______________________

15. ______________________

Head Thorax Crop Stomach

Forewing Jumping Legs Intestine Malpighian tubules

Hindwing Ovipositor Tracheal Tubes Gastric Caecum

Tympanum Abdomen Eye

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How do the internal and external anatomies of the earthworm and grasshopper compare? Which structures are special adaptations that

have allowed that animal to survive in its specific environment? And which structures are common between the two? Organize your

comparison of the two animals into the Venn diagram below. Be sure that you have considered all of the features listed in the word

bank.

Earthworm

Grasshopper

Coelom Clitellum Segments Gastric Caecum

Ovipositor Vascular System Hermaphrodite Metanephridia

Intestine Malpighian tubules Crop

Jumping legs Complete Digestive Tract Gizzard

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