(*) Myxini order of these animals can tie themselves into a knot and are sometimes called slime eels.
Some early examples of these organisms had a hypocercal tail which increases their lift. Some members of this superclass have larval stages termed ammocoetes and have a buccal funnel. The "vertebrate hypothesis" holds that Cyclostomata, a group of these animals, is actually not monophyletic. Some of these ostracoderms are members of Pteraspidomorphi, which possess an armored head covering. The (*) Myxini order of these animals can tie themselves into a knot and are sometimes called slime eels. One member of this order is characterized by their circular arrangement of teeth which surround their mouths. They include hagfishes and lampreys and are less complex than their bony and cartilaginous counterparts. For 10 points, name this class of fish that lacks a mandible.
Some early examples of these organisms had a hypocercal tail which increases their lift.
jawless fishes [Accept "agnatha" or "agnathans" Prompt on "fish"]