Worm Anatomy and Physiology

• Anticoagulants prevent blood clotting and are used by leeches.
• Aortic arches are heart-like structures that pump blood in some organisms.
• Castings refer to nutrient-rich worm waste.
• Annelida is a phylum of segmented worms, including earthworms and leeches.
• Anterior refers to the front end of a worm.
• The anus is the opening where waste exits an organism's body.
• Circumesophageal connectives are nerves that link the brain to the ventral nerve cord.
• The clitellum is a thick band on some worms used for reproduction.
• The crop stores food before digestion.
• Cross-fertilization is when worms exchange sperm for reproduction.
• The cuticle is a thin layer that helps retain moisture.
• The dorsal blood vessel pumps blood forward on the back.
• Dorsal refers to the top or back side of an organism.
• An ectoparasite is a parasite that lives on the outside of a host, such as leeches.
• An endoparasite is a parasite that lives inside a host.
• The esophagus carries food from the mouth to the crop.
• The gizzard grinds food.
• Hermaphroditic organisms have both male and female reproductive organs.
• The intestine absorbs nutrients.
• A leech is a parasitic segmented worm.
• The mouth is where food enters.
• Nematoda is a phylum of roundworms.
• Nephridia removes waste.
• The pharynx is a muscular tube used for swallowing.
• Platyhelminthes is a phylum of flatworms.
• Posterior refers to the back end of the worm.
• The prostomium is a lip-like structure used for digging.
• Segmental ganglia are nerve clusters located in each segment.
• Setae are tiny bristles that aid in movement.
• Skin is used for respiration.
• Subesophageal ganglia are nerve clusters located below the esophagus.
• Supraesophageal ganglia are brain-like nerve clusters located above the esophagus.
• The ventral blood vessel carries blood to the back.
• Ventral refers to the bottom or belly side.

Mollusks

• Adductor muscles open and close the shell in bivalves.
• The anterior part of a mollusk is the front.
• A bivalve is a mollusk with two shells, examples are clams and oysters.
• Calcium carbonate is the main material that forms the shell.
• A cephalopod is a mollusk with tentacles and a large head, examples are octopus and squid.
• A cuttlebone is the internal shell of a cuttlefish.
• The dorsal part of a mollusk is the top or back side.
• Filter-feeding involves straining food from the water.
• The foot is a muscular part used for movement.
• Gastropods include snails and slugs, which may have a single shell or no shell.
• Gills are organs used for underwater breathing.
• The head contains the mouth and sensory organs.
• The horny layer is the outer protective layer of a shell.
• Limestone is a rock material involved in forming shells.
• Lungs are used by land mollusks to breathe.
• The mantle produces the shell.
• Mother of pearl is the shiny inner layer of a shell.
• Mucus is a slippery secretion that aids in movement.
• The periostracum is the outer protective layer of a shell.
• The prismatic layer is the middle layer of a shell and is made of calcium carbonate.
• The nacreous layer is the shiny inner layer that produces pearls.

Three main body parts of a Mollusk are:

• Head, which contains sensory organs and the mouth.
• Foot, which is used for movement or attachment.
• Visceral mass, which contains internal organs.
• A pearl is a hard, round object formed in mollusks.
• Pelecypod is another term for bivalves.
• The posterior part of a mollusk is the back.
• The prismatic layer is the middle layer of a shell.
• The radula is a tongue-like structure with teeth.
• Siphons are tubes that facilitate water movement.
• Tentacles are used for sensory and movement purposes.
• The umbo is the oldest part of a bivalve shell.
• A univalve is a mollusk with one shell (snail).
• A valve is one half of a bivalve shell.
• The ventral part of a mollusk is the bottom or belly side.
• The visceral hump holds internal organs.

Earthworm Systems

• Digestive: Food passes through the mouth, pharynx, esophagus, crop, gizzard, intestine, then out the anus.
• Nervous: Includes the brain (cerebral ganglia), ventral nerve cord, and segmental ganglia.
• Shell: Consists of the periostracum (outer), prismatic layer (middle), and nacreous layer (inner).

Explore the anatomy and physiology of worms, including anticoagulants used by leeches and the function of aortic arches. Learn about key structures such as the clitellum, crop, and dorsal blood vessel. Understand concepts like cross-fertilization and the roles of ectoparasites and endoparasites.