Characteristics and Evolution of Early Vertebrates

Flashcards covering key concepts related to the characteristics and evolution of early vertebrates.

What regulates involuntary actions such as sneezing and heart rate in early vertebrates?

The brain stem, specifically the medulla oblongata.

What were the earliest vertebrates known as?

Ostracoderms, meaning 'shell-skinned'.

What is the primary function of bones in early vertebrates?

Mineral storage, particularly regulating phosphorus and calcium for metabolism.

What type of heart do early vertebrates possess?

A ventral 3-chambered heart.

What do erythrocytes in vertebrates contain that allows them to bind to oxygen?

Hemoglobin.

What are the two main classifications of jawless fishes?

Class Myxini (hagfishes) and Class Pteromzontida (lampreys).

What evolutionary period is known as the 'age of fishes'?

The Devonian period (419-358 mya).

What are the distinct characteristics of Gnathostomes?

They are jawed vertebrates descended from an ostracoderm ancestor.

How many living species of Chondrichthyes exist?

About 970 living species.

What adaptation allows Osteichthyes (bony fishes) to achieve neutral buoyancy?

The swim bladder derived from the gut.

What distinguishes Actinopterygii (ray-finned fishes) from Sarcopterygii?

Actinopterygii includes fishes with ray-finned structures, while Sarcopterygii includes lobe-finned fishes.

What unique feature do coelacanths possess?

They are believed to have been extinct for 70 million years and were rediscovered in 1938.

What body feature allows elasmobranchs, such as rays and sharks, to effectively navigate water?

Their hydrodynamic bodies and asymmetrical heterocercal tails.