Symmetry and Differences Between Echinoderms and Chordates | Animals - assistancedogseurope.info
Differentiate between protostome and deuterostome characteristics. • Identify traits of echinoderms. • Differentiate between the different Chordate subphyla. Most of the deuterostomes belong to one of two groups that include the majority skinned starfish, sea urchins, and their relatives) and the chordates (which close kinship with sea urchins and sea cucumbers -- but both groups share a data continues to accumulate our picture of deuterostome relationships may change. Who would have ever guessed that the sea urchin (an echinoderm) is related to a human (a chordate)? The relationship cannot be seen when Echinoderms and chordates are grouped together because they both are Become a assistancedogseurope.info member to unlock this answer! Deuterostomes: Definition and Characteristics.
Evolution of the jaw. Click image to enlarge Evolution of Legs and the Amniotic Egg Legs and amniotic eggs are two additional derived characters that have played a significant role in the evolution of vertebrates.
The significance of legs in the terrestrial environment is obvious. How do evolutionary biologists think they evolved?
The endoskeletal system of vertebrates consists of the axial elements that are associated with the vertebral column. In addition, more lateral elements, termed the appendicular skeletal system, are found in some groups. The fossil record and other data indicates that the tetrapods, terrestrial vertebrates, arose from lobefin fish, and that legs evolved from these highly modified lobe fins.
The Evolution of Amphibians and Legs. Data suggest that amphibians arose from lobe-fin fish, and that legs arose from the highly modified lobe fins. Click image to enlarge Early vertebrates arose in the oceans, where desiccation was not a problem.
However, with the invasion of land about million years ago, ancient vertebrates had another problem to face, water loss. This was similar to the problem faced by land plants.
The vertebrates evolved a toughened egg that was resistant to drying, the amniotic egg Fig. In reptiles, birds and mammals, the amniotic egg has several unique features, including a specialized membrane system that has many functions, including gas exchange and the transfer of vital nutrients to the developing embryo, and a protective and porous shell.
Carefully remove most of the eggs to reveal the internal organs. Note the large heart, flanked on each side by a prominent lobe of the liver. Lift up the heart to expose the lungs that lie beneath. Lift up the heart, liver, and lungs to expose the esophagus and the top of the stomach.
Note how the esophagus leads up into the pharynx and the mouth. Follow the stomach down to find the small intestine and the large intestine, which leads to the cloaca and the anus. Notice how the intestines are highly coiled to increase surface area for digestion. Cut through one lung to observe its internal structure. What do the architecture of the lung and intestine have in common? Cut through the stomach and lower intestine, and carefully remove the digestive system to expose the urogenital system.
Look for the oval kidneys, lying close to the inner surface of the dorsal body wall. You might see light stripes down the length of each kidney.
Deuterostomes: Echinoderms and Chordates - Biology LibreTexts
These are the adrenal glands. Depending on the season in which the frogs were killed, you might also find star-shaped yellow fat bodies, used for fat storage. In which season would these fat bodies be largest? If your frog is a male, you will find two small ovoid testes lying on top of the kidneys. If your frog is a female, you will find two large ovaries in the same position. In both sexes, you will observe a highly coiled oviduct running along the outer edge of each kidney. In the male frog, this oviduct is a vestigial organ.
Take a deep breath You're doing just fine, though maybe just a tad grossed out. But hold on to your chair or your lab partnerit's about to get a lot worse because Turn your frog over, and remove the skin from the top of the head.
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Now use your surgical scissors to cut through the bones of the skull, starting near the nares nostrilsjust in front of the eyes ewww You will need to very carefully cut and remove the top of the skull in tiny little pieces. It's hard to do this without disturbing the fragile tissues beneath, but give it your best shot Once the brain is in view, identify the olfactory lobe smell brainthe cerebrum thinking brainand the optic lobe seeing brain. Notice that the optic lobes are the largest part of the frog's brain?
What part of the brain would you expect to be largest in a rat? Echinoderms' nervous systems consist of a neural net without any kind of central point. Chordates have a central nervous system, called a notochord or a neural tube. In many chordates, the end of the notochord is enlarged to form a defined, centralized brain -- a feature no echinoderm has.
This goes hand in hand with anteriorization, the formation of a head at the front of an animal. This allows chordates to concentrate their sensory structures in one area. Skeleton Echinoderms and chordates also have very different skeletal structures. Echinoderms have a dermal skeleton, similar to an exoskeleton, or a shell-like structure called a test.
Sea stars have interlocking calcium-based plates that form their dermal skeleton, while urchins have test, covered with spines.