The presence of a notochord unites the group of animals that we are most familiar with. At some point in their lives, all chordates, even humans, have pharyngeal slits, a post-anal tail, a dorsal nerve chord, and a post anal tail.
Lancelet
Most simple, retains all four characteristics their whole life.
Most simple, retains all four characteristics their whole life.
Urochordata
Larva have all four characteristics, adults have pharyngeal gill slits. Tunicates, sometimes called sea squirts, are sea animals are sessile and are permanently attached to rocks or other hard surfaces on the ocean floor; others, such as salps, doliolids and pyrosomes, swim in the pelagic zone of the sea as adults.
Larva have all four characteristics, adults have pharyngeal gill slits. Tunicates, sometimes called sea squirts, are sea animals are sessile and are permanently attached to rocks or other hard surfaces on the ocean floor; others, such as salps, doliolids and pyrosomes, swim in the pelagic zone of the sea as adults.
Vertebrata
Agnatha
Agnathans are a superclass of jawless fish and the most similar to ancient chordates. Paired fins are generally absent and in most cases the skeletons are made of cartilage. They have seven or more paired gill pouches, a light sensitive pineal eye, and do not have a stomach.
Agnathans are a superclass of jawless fish and the most similar to ancient chordates. Paired fins are generally absent and in most cases the skeletons are made of cartilage. They have seven or more paired gill pouches, a light sensitive pineal eye, and do not have a stomach.
Hagfish are able to sneeze out slime as a defense mechanism.
Lamprey have a jawless mouth surrounded by teeth that they use to latch on to larger animal
Chondrichthyes
Sharks, rays, skates, and sawfish belong to a class that contains the cartilaginous fishes: they are jawed vertebrates with paired fins, paired nares, scales, a heart with its chambers in series, and skeletons made of cartilage rather than bone.
Sharks, rays, skates, and sawfish belong to a class that contains the cartilaginous fishes: they are jawed vertebrates with paired fins, paired nares, scales, a heart with its chambers in series, and skeletons made of cartilage rather than bone.
Sharks skin is covered with microscopic teeth called placoid scales or dermal denticles. They are structurally the same as vertebrate teeth, and supported by spines. When touched from head to tail the skin feels very smooth and when touched from tail to head, it feels rough. When flattened by the forward movement of water, the dermal denticles create tiny vortices that reduce hydrodynamic drag and reduce turbulence, making swimming both more efficient as well as quieter compared to that of bony fishes. This has been mimicked in things like racing swimsuits and coatings for the bottoms of boats in order to create a competitive advantage. This technology works so well that it is banned from many competitions.
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For videos on sharks and what makes them unique, check out this link and browse the Ultimate Guide to Sharks videos
Osteichthyes
Of the more than 65,000 living species of chordates, about half are bony fish. The group is divided into the ray-finned fish and lobe-finned fish. "Bony fish," are characterized by their hard internal skeleton, the presence of a bony skull and bony jaws. Tetrapods later evolved from lobe-finned fish.
Of the more than 65,000 living species of chordates, about half are bony fish. The group is divided into the ray-finned fish and lobe-finned fish. "Bony fish," are characterized by their hard internal skeleton, the presence of a bony skull and bony jaws. Tetrapods later evolved from lobe-finned fish.
Amphibia
From the Latin meaning "both lives," Amphibians spend part of their lives (sub-adult or larvae) living in freshwater with gills and part of their lives (adults) on land breathing air with lungs. They are cold-blooded, have no scales, no claws, bony skeletons, four legs, moist thin skin, and a double-loop circulatory system. Many have webbed feet and four digits on their forelimbs.
Metamorphosis
Frog eggs are viviparous and must be kept moist. Even frogs and toads that live in deserts rely on rainstorms so they can lay their eggs in puddles. Salamanders and caecilians have internal fertilization while frogs and toads have external fertilization. Most amphibians go through metamorphosis where, they go from eggs, to larvae, to adults.
Frog eggs are viviparous and must be kept moist. Even frogs and toads that live in deserts rely on rainstorms so they can lay their eggs in puddles. Salamanders and caecilians have internal fertilization while frogs and toads have external fertilization. Most amphibians go through metamorphosis where, they go from eggs, to larvae, to adults.
Some frog species have developed adaptation to allow them to lay eggs and keep them moist.
Poison dart frog (carries tadpoles from rain forest floor to canopy) Darwin’s frog (babies mature in vocal pouch) |