Vertebrates and Invertebrates

Classes of the phylum Annelida- there’s 3!

Polychaeta, Hirudinea, Oligochaeta

What are some examples of Polychaeta, Hirudinea, and Oligochaeta?

• Class Polychaeta: Marine animals with many bristles (setae) and parapodia.

• Class Hirudinea: Leeches that usually have no setae and may be parasitic. 

• Class oligochaeta: Mostly land or freshwater worms like earthworm with fewer setae. 

True of False: Class Polychaeta is the largest class of annelida.

True.

Respiratory system

where earthworms breathe through their moist skin and where oxygen diffuses in and carbon dioxide diffuses out. 

Circulatory system

Earthworms have a closed circulatory system with blood contained in vessels and five aortic arches (hearts). 

 Nerve cord

A ventral nerve cord runs along the underside and carries messages between the brain and body.

Setae

Tiny bristle on the earthworm’s body used for gripping soil and movement. 

Parapodium

Pairs, paddle-like structures used for movement in marine worms. (Polychaetes).

Ventral

The underside or the belly

Dorsal

the top or backside of an animal.

Nephridium

A tube-like structure that removes nitrogenous wastes from the body fluids of the worm. 

Brain

a small mass of nerve tissue that coordinates the worm’s nervous system, located near the mouth. 

Hermaphrodites

organisms that have both male and female reproductive organs. 

Clitellum

a thick, smooth band near the front of the worm that helps form the cocoon during reproduction.

Benefits to the ecosystem

Earthworms improve soil by aerating it, enhancing nutrient cycling, and decomposing organic matter. 

Vertebrae

The individual bones that make up the backbone in vertebrates.

Endoskeleton

An internal skeleton made of bone or cartilage that supports and protects the body.

Adaptation for buoyancy

Features or structures that help an animal float or maintain its position in water.

Lateral line

A sensory organ in fish that detects water movements and vibrations.

Streamlined body plan

A body shape that reduces water resistance, allowing efficient swimming. 

Chondrichthyes

The class of cartilaginous fishes including sharks, rays, and skates.

Chordates

Animals that have, at some stage of life, a notochord, dorsal nerve cord, pharyngeal slits, and a post-anal tail. 

Ampullae of Lorenzini

Electroreceptor organs in sharks and rays that detect electric fields in the water.

Ratfishes

Deep-sea cartilaginous fishes with a single gill slit and a rat-like tail.

Chemoreception

The biological ability to detect chemical stimuli, like smell or taste.

Cartilage\Body shapes of sharks, skates and rays

flexible connective tissue forming the skeleton of cartilaginous fishes like sharks.

Body shapes:

Sharks have a torpedo-shaped body, skates are flattened with rounded fins, and rays are flattened with wing-like fins.

cartilaginous fishes

Fishes with skeletons made of cartilage, such as sharks and rays, often having rough skin and multiple gill slits.

jawless fishes

Primitive fishes without jaws, like lampreys and hagfish, characterized by a sucker-like mouth.