Lab 11: Comparative Anatomy and Digestion of Animals

What are the three animal species that we dissected in Lab 11?

Earthworm, grasshopper, and perch

What does learning anatomy require?

1. Rote memorization

- Monocots have flower parts in threes or multiples thereof

2. Spatial memory

- My lungs are lateral to my heart

Anterior

Refers to the front or forward part of a structure or body

What is another name for "anterior"?

Cranial

Posterior

Refers to the back or rear part of a structure

What is another name for "posterior"?

Caudal

Dorsal

Of, on, or relating to the upper side or back of an animal, plant, or organ (back)

Ventral

Of, on, or relating to the underside (belly) of an animal, plant, or organ (abdominal)

Medial

The direction or position towards the middle/midline of the body

Lateral

The direction or position to the away from the middle/midline of the body

Proximal

Nearer to the center (trunk of the body) or the point of attachment to the body

Distal

A location that is farther away from the center of the body or origin of a structure

Caudal

Towards the tail

(Synonym of posterior & inferior)

Cranial

Toward the head

(Synonym of anterior & superior)

Deep

Away from the body surface

Superficial

Toward or at the body surface

In humans, what are other names for

1. Cranial

2. Caudal

3. Posterior

4. Anterior

1. Superior

2. Inferior

3. Dorsal

4. Ventral

What is the phylum of earthworms?

Annelida

What is the class of earthworms?

Clitellata

What is the order of earthworms?

Haplotaxida

What is the family of earthworms?

Lumbricidae

What is the scientific name of earthworms?

Lumbricus terrestris

Where is the earthworm native to?

Europe, but can be found throughout North America

What is the earthworm considered, pertaining to the ecosystem? Why?

An ecosystem engineer

--> It can change key properties of soil in which it lives.

This affects the ecosystem functioning and biodiversity

How does the earthworm interact with the environment?

It consumes soil and extracts nutrients from dead and decaying organic material

Using the picture on the back of the flashcard, identify the external anatomy of the earthworm

Red: Prostomium

Yellow: Mouth

Green: Clitellum

Blue: Anus

What is the mouth of the earthworm covered by?

Its first segment, prostomium

What is the clitellum and where is it situated?

The clitellum is involved in making gelatinous egg casing during reproduction

It is located near the anterior end

Describe the appearance and texture of the ventral surface of an earthworm

It's typically lighter colored and may feel slightly rough due to containing small, hair-like structures that help the worm grip the soil for locomotion

How can the dorsal surface of an earthworm be distinguished?

By a dark line running along it, known as the dorsal vessel (which is its major blood vessel)

Describe the procedure of dissecting an earthworm

1. Measure the length of the worm in cm

2. Position the worm dorsal side up

3. Pin the mouth to the dissection tray

4. Use forceps to lift the dorsal skin 1-2 cm from the anus

5. Insert scissors to the base of the forceps and cut a line through the anus—avoid cutting too deep to damage internal organs

6. Use scissors and forceps to cut along the dorsal surface

7. Cut the layers above/superficial to the dorsal vessel

8. Insert and position dissection pins at a 45° angle to open and display your worm as you cut

Pharynx

The region between the mouth and esophagus

How do earthworms reproduce?

While they have fully functional male and female sexual organs, they typically reproduce through cross-fertilization

What is cross-fertilization?

Mating with another individual, not with themselves

Seminal vesicles

A larger structure where sperm matures in

Seminal receptacles

Smaller, more spherical structures where the sperm is received in

Aortic arches (heart)

Pumps blood throughout the body

- Has dark, ring-like structures

What structure do the aortic arches surround?

The esophagus

Septa

Membranous structures that separate each segment

Esophagus (of an earthworm)

The tube that transports food from the pharynx to the crop

Crop (of an earthworm)

Stores food (soil)

Gizzard (of an earthworm)

Muscular and contains small rocks

These features help the earthworm grind and mechanically digest food

Intestine (of an earthworm)

The site of chemical digestion (cells in the intestine secrete digestive enzymes) and absorption of nutrients

Anus (of the earthworm)

Where feces is removed

What is the phylum of grasshopper?

Arthropoda

What is the class of grasshopper?

Insecta

What is the order of grasshopper?

Orthoptera

What is the family of grasshopper?

Romaleldae

What is the scientific name of the Eastern lubber grasshopper?

Romalea guttata

Where is the grasshopper native to?

Southeastern and southcentral U.S.

What kind of "-vore" is the grasshopper?

Herbivore

Using the image on the back of the flashcard, Identify the features of the external anatomy of a grasshopper

Red: Fore wing

Orange: Tympanum

Magenta: Head

Yellow: Antenna

Lime green: Simple eye

Dark green: Compound eye

Cyan: Pronotum

Blue: Thorax

Purple: Spiracles

Pink: Tarsus

Lavander: Abdomen

Brown: Tibia

Gray: Femur

Light orange: Hind wing

Antannae

Sensory appendages

What is medial to the compound eyes?

Three ocelli that function as motion detectors

Thorax

Posterior to the head

What is beneath the two sets of wings?

The abdomen

Where does the forewings rest in position to the hind wings?

The forewings rest atop the hind wings

What are the three components that make up each leg of a grasshopper? (Hint: Similar to humans)

Femur, tibia, tarsus

Describe the procedure on dissection a grasshopper

1. Place grasshopper on its back (ventral side facing up)

2. Keeping lower edge of siccors positioned upwards to minimize internal structure damage

3. Cut along lateral body wall on each side of the grasshopper up to its head

4. Make a small cut near the anus to free the lower portion of the integument

5. Pull large flap of integument up and toward the grasshopper's head to reveal internal anatomy, which is largely the digestive system

Esophagus (of a grasshopper)

Is the tube that transports food from the pharynx to the crop

Crop (of a grasshoppper)

Thin-walled and stores food

Gizzard (of a grasshopper)

Muscular and mechanically digests food

Gastric cecae

Pairs of them dump digestive enzymes into the stomach

Stomach (ventriculus) and intestine (hind gut) (of a grasshopper)

Digest and absorb food

What does the hind gut of the grasshopper specifically do?

Absorbs water and houses microbes required to digest cellulose, which is main component of cell walls

Malpighian tubules

Secrete nitrogenous waste into the hind gut for excretion

They are a good landmark for the delineation (border) between the stomach and the hind gut

How are feces excreted in grasshoppers?

As moist pellets from the rectum to the anus

What is the phylum of the perch?

Chordata

What is the class of the perch?

Actinopterygli

What is the order of the perch?

Perciformes

What is the family of the perch?

Percidae

What is the scientific name of the Yellow Perch?

Perca flavescens

What kind of fish is the yellow perch?

Bony fish!

What is the superclass of bony fishes?

Osteichthyes, which contains as many species as the rest of the vertebrates combined!

Where does the perch inhabit?

Temperate freshwater ecosystems throughout North America

What kind of foods does the perch consume?

A range of animals—from tiny zooplankton as larvae to fish eggs, crustaceans, or other fish as adult

Using the imagine on the back of the flashcard, identify the perch's external anatomy

Fins

1. First dorsal fin

2. Second dorsal fin

3. Caudal fin (homocercal tail)

4. Anal fin

5. Pelvic fin

6. Pectoral fin

Other features

7. Gill operculum

8. Mouth

9. Nostril

10. Eye

11. Lateral line

How does ordering begin when identifying the external structures of the perch?

Ordering begins near the anterior/cranial end—the first dorsal fin is closer to the head than the second dorsal fin

Caudal fin

Provides the thrust required to propel the fish

What do the remaining fins (not the caudal fin) typically do?

Largely serve to steer or stabilize the fish

Lateral line

Enables the fish to detect temperature/pressure changes and sense water currents

Describe the procedure on the dissection of the perch

1. Remove the gills operculum using scissors

2. Cut into your perch

3. Use your scalpel to make your incisions

4. Score (cut lightly) the skin, and then cut 1 cm down

5. Peel away the skin

6. Use your scissors to remove the muscles in layers

7. When you get down to the ribs, remove them using your forceps and scissors

How do you cut to see the heart, gill filaments, and gill rakers?

Cut under the head and toward the jaw

Using the image on the back of the flashcard, identify part of the internal anatomy of the perch

1. Epaxial muscles

2. Ctenoid scales (dermal scales)

3. Gill operculum

4. Gill filaments

5. Heart

6. Liver

7. Stomach

8. Membrane of the swim bladder

9. Kidney

Using the image on the back of the flashcard, identify the complete internal anatomy of the perch

1. Gill rakers

2. Gill filaments

3. Brain

4. Spinal cord

5. Kidney

6. Gas gland

7. Oval body

8. Swim bladder

9. Epaxial muscles

10. Hypaxial muscles

11. Gonad (testes or ovary)

12. Urinary bladder

13. Intestine

14. Spleen

15. Stomach

16. Pancreas

17. Pyloric ceca

18. Liver

19. Atrium

20. Ventricle

21. Bulbus arteriosus

Oral cavity (of the perch)

Where food is initially captured

Gill rakers (of the perch)

Protect the gill filaments (involved in respiratory gas exchange) and filter/capture food particles passing over the gills

Esophagus (of the perch)

The tube that transports food from the pharynx to the stomach

Stomach (of the perch)

Stores and digests food

What are the two regions of the stomach (of the perch)

Cardiac region: Closest to the esophagus, which lies posterior to the mouth

Pyloric region: Closest to the intestine

Pyloric cecae

Finger-like projections extending between the stomach and intestine; they are quite small or inconspicuous

Intestine (of the perch)

Extends from the stomach to the anus; absorbs nutrients from food

What is the slick, yellow substance around the intestine of the perch?

A fat tissue that can be removed with your forceps

Liver (of the perch)

Metabolizes fats and carbohydrates, and it produces bile that emulsifies fats and neutralizes acidic chyme (partially digested food) in the intestine

May appear light cream due to the bleaching of the preservative process

Anus (of the perch)

Where feces is removed