FURTHER PHYLOGENETIC CONSIDERATIONS Relationship between Hemichordates and Chordates It is difficult to establish evolutionary relationships between the hemichordates and chordates. Two common characteristics are present between these groups: 1. Dorsal…
PHYLUM CHORDATA (chorda, cord) Phylum Chordata has about 45,000. Its members are very successful at adapting in aquatic and terrestrial environments. Characteristics of the phylum Chordata are: 1. They are…
PHYLUM HEMICHORDATA (hemi, half + chorda, cord) The phylum Hemichordata includes the acorn worms (class Enteropneusta) and the pterobranchs (class Pterobranchia. Members of both classes live in or on marine…
CLASSIFICATION OF HEMICHORDATA & CHORDATA Phylum Hemichordata Hemichordates are widely distributed in shallow, marine and tropical waters. They are present in deep and cold waters. They have soft and wormlike…
HEMICHORDATA & CHORDATES EVOLUTIONARY PERSPECTIVE Hemichordata have some most familiar animals. We are familiar with them because we are members of phylum Chordata. Other members of these phyla are much…
OBJECTIVE OF THE ECHINODERMS Multip e Choice Questions MCQs 1.The origin of ossicle is: (a) Ectoderm (b) Mesoderm (c) Endoderm (d) None 2. Hamel system is derived from: (a)Ectoderm (b)…
SUBJECTIVE QUESTION OF THE ECHINODERMS 1.Describe evolutionary perspective of echinoderms. 2. Give characteristics of Echinoderm. 3. Give relationship of echinoderm with other phyla. 4. Discuss symmetery of echinoderms. 5.Write note…
DEFINITIONS AND KEY POINTS FOR OBJECTIVES OF THE ECHINODERMS TERMS DEFINITIONS Filter feeder The animals ‘‘ Inch filter food particles form the \\ ater current are called filter feeders. Ossieles…
FURTHER PHYLOGENETIC CONSIDERATIONS IN THE ECHINODERMS Most zoologists believe that echinoderms evolved from bilaterally symmetrical ancestors. Radial symmetry was evolved during the transition from active to more sedentary lifestyles. The…
CLASS CRINOIDEA (krinon, lil + oekks, in the form of) Class Crinoidea includes the sea lilies and the leather stars. They are the most primitive living echinodemis. Therefore, they are…
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