Chondrichthyes Anatomy Quiz

Study Notes

Characteristics of Chondrichthyes

Chondrichthyes are distinguished by a cartilaginous skeleton, which provides flexibility and reduced weight compared to bony fish.
They possess two dorsal fins, paired pectoral and pelvic fins, and a heterocercal tail, offering enhanced lift and maneuverability in aquatic environments.

Function of the Spiracle

The spiracle serves as a small respiratory opening, allowing Chondrichthyes to take in water when buried in sand or resting on the ocean floor, ensuring they receive oxygen even when their gill openings may be obstructed.

Heart Structure

The heart of Chondrichthyes typically features a two-chambered design with one atrium and one ventricle, facilitating efficient blood circulation throughout the body.

External Sexual Dimorphism

Males of Chondrichthyes can be externally distinguished by the presence of claspers, elongated structures that aid in the transfer of sperm during mating.

Evolutionary Significance of Fins

Chondrichthyes are the first vertebrates to develop paired fins, a significant evolutionary adaptation that allows for improved balance and movement in water.

Specific Chamber Name in the Heart

The heart includes a specific chamber called the ventricle, which pumps deoxygenated blood to the gills for oxygenation before it circulates through the body.

Gill Opening Characteristics

Chondrichthyes possess lateral gill slits, typically five to seven pairs, which are visibly external, allowing efficient water flow over the gills for respiration.

Scale Type in Chondrichthyes

Their skin is covered with dermal denticles, small, tooth-like structures that reduce drag in water and provide protection from parasites and injuries.

Digestive System Features

The digestive system of Chondrichthyes is characterized by a spiral valve intestine, which increases surface area for nutrient absorption and enhances digestion efficiency.

Description

Test your knowledge about the anatomy of Chondrichthyes, a class of marine predators with a cartilaginous endoskeleton. Learn about their unique features such as ventrally located crescent-shaped mouth, placoid scales, and the presence of paired fins.