Hagfish Day 2024 is on Tuesday, October 15, 2024: From which creatures did fish evolve?

Tuesday, October 15, 2024 is Hagfish Day 2024. Past Hagfish Day Stars Did you miss Hagfish Day

Sponsored Deals

As an Amazon Associate I earn from qualifying purchases.

Check Price

Hagfish are broadly thought to be among the world’s ugliest living animals, made much more repugnant by their manufacture of viscous slime like a defense mechanism. Hagfish Day aims to advertise knowning that in character, beauty isn’t everything – which actually, the Hagfish is really a highly developed and specialized creature worth respect.

FISH WERE THE FIRST VERTEBRATES .. OF EVOLMENT.

The defining characteristic of vertebrates is their backbone, an anatomical feature that first appeared in the fossil record about 500 million years ago, during the Ordovician period. In this article, we'll look at the various groups of vertebrates in the order in which they evolved to create a picture of how vertebrate evolution unfolded to the present day.

FISH EVOLMENT.

Jawless Fish (Class Agnatha) THE FIRST WAS THE JAWLESS FISH.

The first vertebrates were the jawless fish (Class Agnatha

IRThe jawless fish that lived during the

Ordovician period all went extinct by the end of the Devonian period. Yet today there are some species of fish that lack jaws (such as lampreys, and hagfish). These modern day jawless fish are not direct survivors of the Class Agnatha but are instead distant cousins of the cartilaginous fish

Armored Fish (Class Placodermi) T

The armored fish evolved during the Silurian period. Like their predecessors, they too lacked jaw bones but possessed paired fins. The armored fish diversified during the Devonian period but declined and fell into extinction by the end of the Permian period.

Cartilaginous Fish (Class Chondrichthyes)

Cartilaginous fish, better known as sharks, skates, and rays evolved during the Silurian period. Cartilaginous fish have skeletons composed of cartilage, not bone. They also differ from other fish in that they lack swim bladders and lungs.

Bony Fish (Class Osteichthyes)

Members of the Class Osteichthyes first arose during the late Silurian. The majority of modern fish belong to this group (note that some classification schemes recognize the Class Actnopterygii instead of Osteichthyes). Bony fish diverged into two groups, one that evolved into modern fish, the other that evolved into lungfish, lobe-finned fish, and fleshy-finned fish. The fleshy finned fish gave rise to the amphibians.