Describe the difference between jawless and jawed fishesExplain the main characteristics of amphibians, reptiles, and also birdsDescribe the derived features in birds that facilitate flightName and describe the distinguishing features that the three main groups of mammalsDescribe the acquired features that identify primates from other animals

Vertebrates are among the most recognizable biology of the animal kingdom (

). An ext than 62,000 vertebrate types have been identified. The vertebrate species now living represent just a small section of the vertebrates that have actually existed. The best-known die out vertebrates space the dinosaurs, a distinctive group the reptiles, getting to sizes not seen prior to or due to the fact that in terrestrial animals. They to be the dominant terrestrial animals for 150 million years, until they died out close to the finish of the Cretaceous duration in a massive extinction. A good deal is known about the anatomy of the dinosaurs, provided the conservation of your skeletal elements in the fossil record.

You are watching: A key derived character of sharks and rays that distinguishes them from ray-finned fishes is

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Figure 2: (a) Pacific hagfishes are scavengers that live on the s floor. (b) These parasitic sea lampreys connect to your lake trout hold by suction and also use their unstable tongues come rasp away flesh in stimulate to feeding on the trout’s blood. (credit a: modification of occupational by Linda Snook, NOAA/CBNMS; credit transaction b: change of work by USGS)

The skeleton that a hagfish is composed of cartilage, which includes a cartilaginous notochord, which runs the length of the body, and a skull. This notochord offers support to the fish’s body. Although they room craniates, hagfishes are not vertebrates, since they execute not replace the notochord v a vertebral column throughout development, as execute the vertebrates.

The clade Petromyzontidae includes roughly 40 varieties of lampreys. Lampreys are similar to hagfishes in size and shape; however, lampreys have a mind case and also incomplete vertebrae. Lampreys lack paired appendages and bone, as perform the hagfishes. Together adults, lampreys are identified by a toothed, funnel-like suck mouth. Some varieties are parasitic as adults, it is registered to and also feeding top top the human body fluids the fish (

b). Most types are free-living.

Lampreys live mostly in coastal and new waters and also have a an international temperate an ar distribution. All species spawn in new waters. Eggs are fertilized externally, and the larvae space distinctly different from the adult form, security 3 come 15 years as suspension feeders. Once they achieve sexual maturity, the adult reproduce and die in ~ days. Lampreys have actually a notochord together adults.

Jawed Fishes

Gnathostomes or “jaw-mouths” space vertebrates that have jaws and also include both cartilaginous and bony fishes. One of the most far-reaching developments in early on vertebrate advancement was the origin of the jaw, which is a hinged structure attached to the cranium that enables an pet to grasp and also tear that food. The development of jaws allowed early gnathostomes to make use of food sources that to be unavailable come jawless fishes.

The clade Chondrichthyes, the cartilaginous fishes, is diverse, consist of of sharks (

a), rays, and skates, together with sawfishes and also a couple of dozen species of fishes dubbed chimaeras, or ghost sharks. Chondrichthyes have actually paired fins and also a skeleton make of cartilage. This clade arose roughly 370 million years back in the middle Devonian. They room thought to have actually descended from an extinct group that had a skeleton do of bone; thus, the cartilaginous skeleton the Chondrichthyes is a later development. Components of the shark skeleton room strengthened through granules of calcium carbonate, yet this is no the same as bone.

Most cartilaginous fishes live in naval habitats, v a few species life in fresh water for some or all of their lives. Many sharks space carnivores that feed ~ above live prey, either swallowing it totality or making use of their jaws and teeth come tear it right into smaller pieces. Shark this likely evolved from the jagged scales the cover their skin. Some types of sharks and rays are suspension feeders that feed ~ above plankton.

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Figure 4: The (a) sockeye salmon and also (b) coelacanth are both bony fishes of the Osteichthyes clade. The coelacanth, sometimes dubbed a lobe-finned fish, was thought to have gone die out in the late Cretaceous duration 100 million years ago until one was found in 1938 between Africa and Madagascar. (credit a: change of job-related by Timothy Knepp, USFWS; credit b: modification of job-related by Robbie Cada)Amphibians

Amphibians space vertebrate tetrapods. Amphibia includes frogs, salamanders, and caecilians. The ax amphibian means “dual life,” which is a referral to the metamorphosis that countless frogs experience from a tadpole come an adult and the mixture that aquatic and also terrestrial environments in their life cycle. Amphibians evolved in the Devonian period and to be the faster terrestrial tetrapods.

As tetrapods, many amphibians are identified by 4 well-developed limbs, back some types of salamanders and also all caecilians possess just vestigial limbs. An essential characteristic that extant amphibians is a moist, permeable skin, achieved by rubber glands. The moist skin allows oxygen and also carbon dioxide exchange v the environment, a procedure called cutaneous respiration. All living adult amphibian varieties are carnivorous, and some terrestrial amphibians have actually a difficult tongue the is provided to catch prey.

Amphibian Diversity

Amphibia make up an approximated 6,500 extant species that inhabit tropical and temperate regions roughly the world. Amphibians can be divided into 3 clades: Urodela (“tailed-ones”), the salamanders and also newts; Anura (“tail-less ones”), the frogs and also toads; and also Apoda (“legless ones”), the caecilians.

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Living salamanders (

a) include approximately 500 species, some of which room aquatic, others terrestrial, and some the live ~ above land just as adults. Adult salamanders usually have a generalised tetrapod body setup with 4 limbs and a tail. Part salamanders space lungless, and respiration occurs through the skin or external gills. Part terrestrial salamanders have primitive lungs; a couple of species have both gills and lungs.

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Figure 5: (a) many salamanders have actually legs and a tail, yet respiration varies among species. (b) The Australian eco-friendly tree frog is a nocturnal predator that lives in the canopies the trees near a water source. (credit a: alteration of work-related by Valentina Storti; credit transaction b: modification of work by Evan Pickett)