What are Chordates?
Chordates include the vertebrates and a couple close cousins, the tunicates (sea squirts) and lancelets, primitive aquatic animals. In scientific classification, Chordata is one of 38 phyla of animals, one of the “big nine” along with Mollusca, Porifera, Cnidaria, Platyhelminthes, Nematoda, Annelida, Arthropoda, and Echinodermata. The precise origin of the chordates is unknown, but fish- or lancelet-like fossils from the Cambrian show that they existed at least 530 million years ago, during the so-called Cambrian explosion of biodiversity. The defining characteristics of chordates are a hollow dorsal nerve cord, a notochord, pharyngeal slits/pharyngeal pouch, an endostyle, and a post-anal tail. The earliest chordates are found in the Chengjiang fauna of fossil beds in China, dated to 520-530 million years ago. Eight possible chordates are found in these fossils beds. The most famous is Myllokunmingia, a primitive, probably agnathan (jawless) fish, the first vertebrate to appear in the
How many kinds of chordates do you know? Chordates are active animals with bilaterally symmetric bodies that are longitudinally differentiated into head, trunk and tail. The most distinctive morphological features of chordates are the notochord, nerve cord, and visceral clefts and arches. There are 5 kinds of chordates in the world: fishes, amphibians, reptiles, birds, and mammals. In the essay I will talk about the common and distinguishing characteristic between each kind of chordates. First, the animals living in water that we know they are fishes. Fishes are poikilothermal, because they could charge their blood temperature with the temperature of the surroundings. Fishes were the earliest vertebrates and presumably evolved from a group of aquatic lower chordates; the terrestrial vertebrates evolved from fishes. Fishes can not live on the land, because they can not breathe on land. For example, if you take a fish out the water, you will discover that fish die in later. The reason is
1. Phylum Chordata includes the tunicates, lancelets, and the vertebrates. Vertebrates include fishes, amphibians, reptiles, birds, and mammals. 2. Chordates share four characteristics: a notochord, a dorsal hollow nerve cord, pharyngeal pouches or slits, and a postanal tail. 3. The hemichordates may bridge echinoderms and chordates. 25.
Page Description: Enrich your study of vertebrates with this science printable. Students will answer questions about chordates and label the parts of a lancelet. Grade Levels: 6 – 12 The full page is available ONLY to subscribers. Sign up today for a free 7-day trial to get access to this page and all of the 20,000 items on TeacherVision.
