Jawless fishes Exam 3

Vertebrates

Chordates with a spinal column, distinguished from invertebrate chordates by having a vertebral column and a distinct head with sensory organs.

Neural Crest

A unique group of embryonic cells in vertebrates that forms many vertebrate structures, including neurons and melanocytes.

Agnatha

Jawless vertebrates, which include lampreys and hagfish.

Hagfish

A class of jawless fish (Myxini) known for their slime production and scavenging behavior.

Lampreys

Jawless fish (Petromyzontida) that are often parasitic and have an anadromous life cycle.

Myxini

Class containing hagfishes that are characterized by their naked skin and slime glands.

Petromyzontida

Class of lampreys, a type of jawless fish known for their parasitic and non-parasitic forms.

Neurulation

The process during embryonic development in which the neural crest is formed.

Chondrichthyes

A class of cartilaginous fishes, including sharks and rays.

Ostracoderms

Early jawless fishes that had armor and are now extinct.

Sarcopterygii

Lobe-finned fishes, some of which are ancestors of terrestrial vertebrates.

Actinopterygii

Ray-finned fishes, a diverse class of bony fishes.

Tetrapoda

Four-limbed vertebrates that evolved from lobe-finned fishes.

Gnathostomata

Craniata with jaws, encompassing many vertebrate classes including fish and tetrapods.

Neural Plate

A structure in the developing embryo that gives rise to the neural tube.

Evolution of Jawless Fishes

Refers to the history and characteristics of early vertebrates like ostracoderms, including their evolutionary significance.

Gill Arches

Structures derived from neural crest cells that contribute to the formation of gills and facial bones in vertebrates.

Ectoderm

The outermost layer of cells or tissue in an embryo that develops into the neural crest.

Internal Gills

Respiratory structures found in jawed fishes that allow for gas exchange.

Single-loop Circulation

A type of circulatory system found in jawless fishes where blood flows in a single circuit from the heart to the gills and back.