Introduction to Annelids and Nematodes

This flashcard set covers the vocabulary and biological structures of Nematodes and Annelids, including specific earthworm anatomy and reproductive processes.

Loco Trochophoric

The umbrella group containing mollusks, flatworms, and annelids that share a free-living larval stage called a trochophore.

Nematodes

Unsegmented roundworms that are typically pseudocoelomates with a tubular digestive tract and include many parasitic species such as pinworms and hookworms.

Ascaris

A type of intestinal roundworm represented in the lecture that has species capable of infecting humans.

Filariasis

A disease caused by filarial worms that clog the lymphatic system, leading to severe swelling, primarily found in parts of Africa.

Annelids

Segmented worms such as earthworms, polychaetes, and leeches that are coelament protocells and exhibit bilateral symmetry with a complete digestive tract.

Setae

Also referred to as bristles or sette, these external structures on annelids help anchor their bodies during movement.

Septae

Internal partitions that divide the body of an annelid from one segment to the next.

Polychaeta

A class of mostly marine annelids characterized by having many bristles and parapodia appendages.

Parapodia

Appendages found on polychaetes that stick out and bear numerous bristles (setae).

Oligochaeta

The class of annelids, including earthworms, that possess a few short bristles used for anchoring in soil.

Circular and Longitudinal Muscles

Two layers of muscle fibers used by earthworms to contract and expand their bodies for movement.

Prostomium

The very tip of the earthworm's anterior end, located just before the mouth.

Peristomium

The second segment of an earthworm that surrounds the mouth.

Seminal Receptacles

Structures located between segments $9$ to $11$ in earthworms that store sperm received from another worm during reproduction.

Gonopores

Openings found around segment $15$ for the release of sperm and eggs; earthworms are hermaphrodites and possess both male and female versions.

Clitellum

A swelled-up portion of fused segments about a third of the way back from the mouth that secretes a mucus band for egg fertilization.

Pharynx

A band of muscle tissue surrounding the first part of the earthworm's esophagus that pulls food down toward the crop.

Crop

A temporary storage area for soil and food within the earthworm's digestive tract.

Gizzard

The organ in the earthworm's digestive system responsible for the physical breakdown of food.

Aortic Arches

The $5$ pairs of simple hearts that pump blood in the earthworm's closed circulatory system.

Nephridia

Primitive kidney-like structures in earthworms that collect and excrete waste.

Nephrostome

The gathering point at the end of a nephridia where waste is collected from the body.

Nephritic Pores

Also called excretory pores, these are the openings on the body surface through which waste is eliminated.

Typhlosole

An internal fold in the earthworm's intestine that increases surface area for digestive enzymes to contact food particles.

Hirudinea

The class of annelids consisting of leeches, which are ectoparasites that lack setae and use suckers for attachment.

Anticoagulant and Anesthetic

Substances secreted by leeches to prevent blood clotting and numb the prey's skin during feeding.