short note
i
) Hemichordata.
Answers
Answer:
Hemichordata is a unique phylum of marine invertebrates found in a wide range of depths and habitats. Two distinctly different body plans exist in this phylum: the large, solitary acorn worms (Class Enteropneusta), and the filter-feeding colonies of the class Pterobranchia. The hemichordate body is divided into three parts: proboscis (protostome), collar (mesosome) and trunk (metasome) - reflecting an underlying tricoelomate organization (see below). Hemichordates express all the attributes of Deuterostomia and at least one unique structure, the stomochord, a cartilaginous element that projects into the protocoel and supports the heart/kidney complex. The principal nervous system occurs dorsally in the collar region, and there is also an extensive epidermal nerve net. They have a pharynx in the trunk region, which may contain one or more pairs of gill slits. They have several chordate traits that make the hemichordates an important target of research for understanding deuterostome and chordate evolution (Brown et al. 2008).
Explanation:
Answer:
Because the buccal diverticulum, a tubular outgrowth from the mouth cavity forward into the proboscis.
Explanation:
- Hemichordata is a unique phylum of marine invertebrates found in a wide range of depths and habitats.
- Two distinctly different body plans exist in this phylum: the large, solitary acorn worms (Class Enteropneusta), and the filter-feeding colonies of the class Pterobranchia.