Lab Week 3

Nematoda General Features

Round worms, no internal segments or septa, pseudocoelomates, sexually dimorphic, membrane bound cuticle, ecdysis, longitudinal muscles, complete digestive tract, and eutely.

Are Nematoda acoelomates, pseudocoelomates, or coelomates?

Pseudocoelomates

Sexual Dimorphism

When males and females of the same species have different physical appearances beyond just their reproductive organs.

What gender is the left?

Female

What gender is the right?

Male

What gender is the bigger one?

Female

What gender is the smaller one?

Male

What Phylum is this?

Phylum Nematoda

What gender is this?

Male

1

Intestine

2

Vas Deferens

3

Testes

4

Longitudinal Muscle

5

Pseudocoelom

6

Cuticle

Testes

The male reproductive organ that produces sperm, seen as a coiled tube in the cross section.

Vas Deferens

Also called ductus deferens, it is the tube that carries sperm from the testes to the seminal vesicle.

Seminal Vesicle

A storage organ for sperm before it is released during mating.

Intestine and Intestinal Lumen

The digestive tube and its hollow center where food is digested and nutrients are absorbed.

Pseudocoelom

The fluid-filled body cavity that is not fully lined by mesoderm and functions as a hydrostatic skeleton.

Cuticle

The tough, flexible, non-living outer covering that protects the worm and is molted during growth.

Ovary

The female reproductive organ that produces eggs, seen as coiled tubes in the cross section.

Oviduct

The tube that carries eggs from the ovary to the uterus.

Uterus

The organ where eggs are stored before being released.

What Phylum is this?

Phylum Nematoda

What gender is this?

Female

1

Intestine

2

Ovary

3

Oviduct

4

Uterus

5

Pseudocoelom

6

Longitudinal Muscle

7

Lateral Line

8

Cuticle

Annelida General Features

Bilateral symmetry, commonly called segmented worms, classified based upon septa, setae and appearance of clitellum, acephalic, partitioned coelom common, cuticle present as a surface secretion not membrane bound, and classes include Oligochaeta, Polychaeta, and Hirudinida.

Do Annelida have radial or bilateral symmetry?

Bilateral

Class Oligochaeta

Distinguishing features include having few setae per segment, being acephalic (no head), having a clitellum, and living in freshwater or terrestrial environments. Ex.) Earthworms like Lumbricus terrestris.

Class Polychaeta

Distinguishing features include having many setae per segment, having a well-developed head with eyes and tentacles, having parapodia for movement, and living in marine environments. Ex.) Marine worms like Nereis.

Class Hirudinida

Distinguishing features include having no setae, having anterior and posterior suckers for attachment, having a fixed number of segments, and being parasites or predators that feed on blood or small invertebrates. Ex.) Leeches like Hirudo medicinalis.

What Phylum and Class is this organism?

Phylum Annelida, Class Oligochaeta

1

Prostomium (“lip”)

2

Mouth

3

Clitellum

4

Setae

5

Metameres (segments)

6

Cuticle

What is this a dissection of?

Annelida

1

Crop

2

Seminal Vesicles

3

Seminal Receptors

4

Mouth

5

Pharynx

6

Dorsal Blood Vessel

7

Esophagus

8

Gizzard

9

Nephridia

10

Intestine

11

Aortic Arch (heart)

Setae

Stiff hair-like bristles on the outside of each segment that provide traction for movement through soil.

Mouth

The opening at the anterior end where food enters.

Prostomium

The "lip" that overhangs the mouth and helps sense the environment.

Clitellum

A swollen, glandular band of segments that secretes a mucous cocoon for egg deposition during reproduction.

Metameres

The individual body segments that make up the earthworm.

Cuticle

The thin, non-living outer layer that protects the body surface.

Pharynx

The muscular organ that pumps food into the digestive tract.

Esophagus

The tube that connects the pharynx to the crop.

Crop

A storage organ for food before it enters the gizzard.

Gizzard

A muscular organ that grinds food into smaller pieces.

Seminal Vesicles

Organs that store sperm produced by the earthworm.

Seminal Receptacles

Organs that receive and store sperm from a partner during mating.

Aortic Arches

Also called hearts, these are muscular vessels that pump blood through the circulatory system.

Nephridia

Osmoregulatory structures found in annelids and other invertebrates that filter fluid from the coelom and excrete waste while reabsorbing useful ions and water. In earthworms, they are paired in each segment and help maintain fluid and ion balance.

What Phylum does this cross section belong to?

Phylum Annelida

1

Coelom

2

Circular Muscle

3

Lumen of Intestine

4

Hypodermis

5

Cuticle

6

Typhlosole

7

Longitudinal Muscles

8

Chlorogogue Cells

9

Seta

10

Ventral Nerve Cord

11

Ventral Vessel

Hypodermis

The cellular layer beneath the cuticle that secretes the cuticle.

Circular Muscle

Muscle fibers that run around the body and help with movement and shape change.

Longitudinal Muscle

Muscle fibers that run lengthwise along the body and help with movement and shape change.

Dorsal and Ventral Blood Vessels

The main blood vessels that run along the top and bottom of the earthworm and circulate blood.

Coelom

The true body cavity fully lined by mesoderm that contains the internal organs.

Typhlosole

A fold of the intestine that increases surface area for nutrient absorption.

Chlorogogue Cells

Cells around the inner surface of the typhlosole and outer surface of the intestine that store glycogen and fats and help detoxify harmful substances.

Mollusca General Features

Head-foot animals, triploblastic, bilateral symmetry, coelomates of limited size, muscular foot that is significantly modified in cephalopods, and visceral mass in mantle cavity.

Are Mollusca Diploblastic or Triploblastic?

Triploblastic

Do Mollusca have radial or bilateral symmetry?

Bilateral

Are Mollusca Acoelomates, Pseudocoelomates, or Coelomates?

Coelomates

Class Gastropoda

A class of Mollusca that includes snails and slugs.

Class Bivalvia

A class of Mollusca that includes clams, oysters, and mussels.

Class Cephalopoda

A class of Mollusca that includes squid, octopus, and nautilus.

Which side of the Mollusca is 1?

Anterior

What is 2 referring to?

Valves