Genital and excretory systems closely related, utilizing common ducts and pathways. They are all ways of distinguishing taxa based on primitive versus derived traits. Use them to help you memorize and classify the taxa we will be talking about this week. The Agnatha are referred to as a superclass. In general, this group shares the common characteristics of jawlessness and cartilaginous skeleton.
Agnathans possess no paired fins , a single nostril, and a two-chambered heart.
Lampreys are parasitic as adults, in which they attach to other fishes with their suction-like mouths and rasp a hole in the skin. Their buccal glands secrete an anticoagulant to ensure free-flowing food source. Hagfishes feed on detritus and carrion and use sensitive tentacles around their mouths in locating prey. Bizarre-looking marine fish lacking scales, and with flat, bony plates instead of teeth. Scales covering skin.