Answers to Objectives
pp. 441.
- Chordates- have pharynx which can function as digestive and respiratory. These organism have a notochord and are classified as deuterostomes. Echinoderms have spicules on their skin and they have exoskeletons made of calcium carbonate.
- Phylum Chordata- have notochords and tubular dorsal nerve cords. They also have muscular tube obtained from mesoderms. Pharynx walls have gill slits and most of the organimsms have tails. Phylum Echinodermata-organisms that are unsegmented, bilateral in larvae and usually have a radial symmetry in adults. Phylum Hemichordata are also considered as the sisters of echinoderms and most of them have shorter notochords and possess gill slits.
- Echinoderms has external spines, radial symmetry and hard outer coverings. Chordates have vertebral columns for body framework and have gill slits for respiration.
- Compared to the primitive phyla, echinoderms have a unique outer coverings made of calcium carbonate whilst chordates have a complete network of nerves attached to vertebrae for locomotion and body framework.
- Echinoderms have circular bodies that contains a network of water-filled canals that are linked to their tube feet. They use their feet for eating, respiration and sensory reception and locomotion.
- Blastula is a ball of cells that forms into a hollow ball of cells with a hole during the embryo stage. For the protostomes, the hole becomes the mouth whilst for deuterostomes, it becomes the anus.
- Protostomes consists of phyla: Platyhelminta, Nematoda, Coelenterata, Mollusca, Arthropoda and Annelida. Deuterostomes are Chordata and Echinodermata.
Questions for Further Study Answer Key:
- Although Echinoderms are closely related to phylum Chordata; still Chordata have an advantage over the echinoderms because they have nervous system and vertebrae.
- Because it determines the organisms morphology and it will help scientists to study their class.
- Because they do not have brains (CNS), it does not mean they are useless. The arms extending from the radial body serve them as their lungs, sensory reception, locomotion and importantly, for digestion.
- Animals are deprived of their natural habitats; hence they roam around to gather food but end up being hunted by colonists either for game or for food as well.
- The bilateral symmetry of the vertebrates is the ‘mirror-image’ of the other body half. If an organism has two legs on the other side, another mirror-image would be another two legs on the other side of the body, thus making it four.
- Cuticle is used for protecting the soft body parts of the fingers and toenails. Arthropods need their cuticles to regulate the body temperature and also as a protective covering.
- Mandibles are a pair of appendages located near the teeth of insects and most vertebrates and is used for eating. Octopus’s mandibles are made of muscles and is located beneath its body.
- Early animals came from simple cells. Mammals are the most advanced because they have complete physical and internal body parts. They have the ability to feed their young and insulate themselves in winter.
- Mammals have superior locomotion than birds because they can run fast in order to hunt for food. This ability puts them in advantage compared to birds and they also have sense of balance as well.
- Reptile scales, mammal hair and bird feathers are forms of physical covering. These act as a shield to external dangers and also as a form of insulator when the weather is cold.
- Taxonomy Groups Table:
References
Campbell, N., & Reece, J. (2007). Biology. San Francisco: Pearson Publications
Simpson, G. (1961). Principles of Animal Taxonomy. New York: Columbia University Press.
