What two main groups of fish are there what are the two main groups of jawed fishes?

What two main groups of fish are there what are the two main groups of jawed fishes?

Gnathostomes: Jawed Fishes. Gnathostomes, jawed vertebrates, can be divided into two types of fish: Chondrichthyes (cartilaginous fish) or Osteichthyes (bony fish).

What are the two classes of jawed fish?

JAWED FISH There are two classes of living fish with jaws: the Chondrichthyes (the cartilaginous fish or elasmobranchs) and the Osteichthyes (the bony fish).

What are the 2 classes of jawed Gnathostomata?

The class is divided into two subclasses: Elasmobranchii (sharks, rays and skates) and Holocephali (chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class).

What are the sensory structures used in different types of jawed fish?

Sharks, together with most fishes and aquatic and larval amphibians, also have a row of sensory structures called the lateral line, which is used to detect movement and vibration in the surrounding water, and is often considered to be functionally similar to the sense of “hearing” in terrestrial vertebrates.

What is the distinguishing feature of each of the fish classes?

Although they are bony fish, they do not have scales; instead, they have a thin skin stretched over a series of bony plates arranged in rings throughout their body….Classification of Fishes.

Class	Sarcopterygii
Scales	Yes
Fins	Yes, lobe
True Vertebral Column	Yes
Bone Tissue	Yes

What characteristics most commonly distinguish different orders of fish?

With the exception of some primitive species, most fish have common characteristics that include gills, scales, fins and bony skeletons. Some characteristics that differentiate fish include the shape of their heads, where their mouths are located, fin type and location, and average adult size.

What features are shared by all of the jawed fish?

All jawed fish have a cartilaginous endoskeleton, gills and scales.

What were the 1st jawed fish describe them and when they first evolved in the geological time scale?

Placodermi: plate-skin fishes The first record of the jawed Placodermi is from the Early Devonian, about 400 million years ago. The placoderms flourished for about 60 million years and were almost gone at the end of the Devonian. Nothing is known of their ancestors, who must have existed in the Silurian.

What is the difference between Agnatha and Gnathostomata?

The key difference between Agnathans and Gnathostomata is that Agnathans are organisms that do not possess a jaw while Gnathostomata are organisms with jaws. Agnathans are jawless fish. Gnathostomata are fish that have jaws.

What are the two most important derived characters shared by the Gnathostomes?

A vertically biting device called jaws, and which is primitively made up by two endoskeletal elements, the palatoquadrate and Meckelian cartilage, and a number of dermal elements called teeth, sometimes attached to large dermal bones.

What are the two extant groups of jawless fish How are they similar How are they different?

Classification of Jawless Fish There are two living groups of jawless fish, with about 100 species in total: lampreys and hagfish (Figure below). Although hagfish belong to the subphylum Vertebrata, they do not technically have vertebrae (though they do have a skull), whereas lampreys do have vertebrae.

What era and period is jawed fish diversity?

The first record of the jawed Placodermi is from the Early Devonian, about 400 million years ago. The placoderms flourished for about 60 million years and were almost gone at the end of the Devonian.

How are jawless fishes different from other vertebrates?

Jawless fishes—the present day hagfishes and lampreys—have a distinct cranium and complex sense organs including eyes, distinguishing them from the invertebrate chordates. The jawed fishes evolved later and are extraordinarily diverse today. Fishes are active feeders, rather than sessile, suspension feeders.

Where are the pelvic fins located in a jawed fish?

Pectoral fins are typically located on the anterior body, and pelvic fins on the posterior. Evolution of the jaw and paired fins permitted gnathostomes to expand their food options from the scavenging and suspension feeding of jawless fishes to active predation.

How did the jaws of fishes come about?

In fact, one of the most significant developments in early vertebrate evolution was the development of the jaw: a hinged structure attached to the cranium that allows an animal to grasp and tear its food. Jaws were probably derived from the first pair of gill arches supporting the gills of jawless fishes.

Which is the first jawed vertebrate in the world?

Evolution of fish. The first jawed vertebrates probably developed during the late Ordovician period. They are first represented in the fossil record from the Silurian by two groups of fish: the armoured fish known as placoderms, which evolved from the ostracoderms; and the Acanthodii (or spiny sharks).