Can you please help me with answers. 18.1 Evolution of Chordates and lance- The
ID: 253375 • Letter: C
Question
Can you please help me with answers. 18.1 Evolution of Chordates and lance- The evolutionary tree of the chordates (Fig. 18.1) shows that some chordates, notably the tunicates lets, are not vertebrates. These chordates retain the notochord and are called the invertebrate chordate Explain the term invertebrate chordates. The other animal groups in Figure 18.1 are vertebrates in which the notochord has been replaced by the vertebral column. Fishes include three groups: the jawless fishes were the first to evolve, followed by the cartilaginous fishes and then the bony fishes. The bony fishes include the ray-finned fishes (the largest group of vertebrates) and the lobe-finned fishes. The first lobe-finned fishes had a bony skeleton, fleshy appendages, and a lung. These lobe-finned fishes lived in shallow pools and gave rise to the amphibians. What three features called out in Figure 18.1 evolved among fishes? The terrestrial vertebrates are all tetrapods because they have four limbs. The limbs of tetrapods appendages just like those of arthropods. Amphibians still return to the water to reproduce, but reptiles are fully adapted to life on land because among other features they produce an amniotic egg. The amniotic egg is so named because the embryo is surrounded by an amniotic membrane that encloses amniotic fluid. Therefore, amniotes develop in an aquatic environment of their own making. Do all animals develop in a water environment?Explain. In placental mammals, such as humans, the fertilized egg develops inside the female, where the unborn mam- mal receives nutrients via the placenta. Reptiles (including birds) and mammals have many other adaptations that are suitable to living on land, as we will stress in later sections. Tetrapodi bony lobe-inned fishes amphbians reptlesmmmals tunicateslancelets Jless fishes shes fisthes mammary glands amnionic e9g ungs bony skeleton Figure 18.1 Phylogenetic tree of the chordates. Evolution of chordates is marked by at least seven innovations. ancestral chordate 18-2 238 Laboratory 18 The Vertebrates
Explanation / Answer
Explain the term invertebrate chordates: Invertebrate chordates retain the notochord but lack a backbone or a vertebral column. Common Characteristics of invertebrate chordates include Endoskeleton, Notochord: Stiff rod along the back of the animal. The notochord is attached to muscles necessary for support and locomotion. Hollow Dorsal Nerve Cord: Travels the length of the body. Pharyngeal Slits: Found along the walls of the pharynx and Postanal Tail.
What three features called out in figure 18.1 evolved among fishes? Jaws, bony skeleton, lungs
The limbs of tetrapods are leg like jointed appendages just like those of arthropods.
Do all animals develop in a water environment Yes. Explain: The reptiles, birds and mammals develop within the aminotic membrane, which contains aminotic fluid.