Retrogressive Metamorphosis in Urochordates Metamorphosis is a change from the juvenile to adult stage in which larval stage is quite different from the adult stage. In retrogressive metamorphosis the larva possesses advanced characters which are lost during the development and the adult is either sedentary or degenerated with primitive characters. urochordates Urochordates have four fundamental characteristics of chordates in the larval stage but adult urochordates possess neither a notochord nor a dorsal nerve cord. The tadpole-like larvae are planktonic and possess the fundamental chordate characteristics that help them in finding a substratum for attachment.
B. Larval cephalochordates and adult urochordates. C. Larval urochordates and adult cephalochordates. Answer Save. 1 Answer. Relevance. Mohsin Raza. 8 years ago. Favorite Answer. A. Notochord, or a rod of vacuolated cells, encased by a firm sheath that lies ventral to the neural tube in vertebrate embryos and some adults. The only chordate characteristics retained in adult urochordates are the pharyngeal gill silts. These are used in suspension feeding where they support a mucus net within the pharyngeal chamber to capture particles drawn through the incurrent siphon. The filtered seawater is expelled from the chamber via an excurrent siphon, and the mucus with.
Click to see full answer. Consequently, what are most tunicate adults? Tunicate is the common name for all of the adult Urochordates, which do not resemble most other sexpert.xyz tunicates are not free to move around and their body is covered by an exoskeleton called a tunic. The adult phase of the tunicate lacks the notochord and tail but still has a highly developed . adult tunicate. Why do adult urochordates (tunicates) lack notochords, even though larval urochordates have them? Larvae use notochords to _____. aid in swimming; adults are sessile and thus no longer propel themselves. If a tunicate's pharyngeal gill slits were suddenly blocked, the animal would have trouble _____.
The adult appendicularian resembles the tadpole larva of other tunicates. The body is enveloped in a “house,” with which the animal nets food. Small (usually around five millimetres in length, including the tail) and simple, appendicularians do not form colonies. They spend their entire lives in the open sea. 13) Adult urochordates do not have notochords, even though larval urochordates have them. Larval urochordates use their notochord to: A) aid in swimming; adults are sessile and thus no longer propel themselves. B) induce tissue differentiation; in adults, tissue is already differentiated. C) stiffen their bodies; in adults, the notochord is replaced by a column of bone.