GENERAL HISTOLOGY

Detailed explanation-1: -Chordates are eucoelomate deuterostomes, and probably share a common ancestor with echinoderms. Three important characteristics unite the Phylum Chordata. At some point in their life cycle, all chordates have a notochord, a dorsal hollow nerve cord, and pharyngeal gill slits.

Detailed explanation-2: -Echinoderms are the most closely related phylum to the phylum Chordata, which includes many complex organisms such as humans. Their shared common ancestor was likely a bilaterally symmetrical organism with a cephalized (centralized in a head region) nervous system.

Detailed explanation-3: -The echinoderms and the chordates are deuterostomes, while all other invertebrates are protostomes. Due to the abundance and calcareous shells of echinoderms, these organisms have been well preserved as fossils.

Detailed explanation-4: -The word deuterostome comes from the Greek word meaning “mouth second, ” indicating that the anus is the first to develop. The phyla Echinodermata and Chordata (the phylum in which humans are placed) both belong to the superphylum Deuterostomia.

Detailed explanation-5: -Solution : In Echinodermates and chordates, the anus of the digestive tract develops first in the embryo and the mouth is formed later. The animals of these two phylum which possess this body plan are called deuterostomes.