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

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 (
