The following questions refer to the description below.
While on an intersession course in tropical ecology, Kris pulls a large, snakelike organism from a burrow (the class was granted a collecting permit). The 1-m-long organism has smooth skin, which appears to be segmented. It has two tiny eyes that are hard to see because they seem to be covered by skin. Kris brings it back to the lab at the field station, where it is a source of puzzlement to the class. Kris says that it is a giant oligochaete worm; Shaun suggests it is a legless amphibian; Kelly proposes it belongs to a snake species that is purely fossorial (lives in a burrow).
-The adaptation of the body shape of snakes has resulted in one of their lungs becoming vestigial. Another adaptation (to a fossorial lifestyle)is snakes' absence of limbs. If the "mystery organism" has also become adapted to a fossorial lifestyle, though its ancestors moved about on the surface, then which structures should one expect to find upon dissecting the organism?
1)reduced or absent pelvic and/or pectoral girdles
2)metanephridia
3)hydrostatic skeleton
A) 1 only
B) 1 and 2
C) 1 and 3
D) 2 and 3
E) 1, 2, and 3

Question

Quizplus · Accepted Answer

If the organism has adapted to a fossorial lifestyle, it would have lost its limbs and therefore would not need pelvic or pectoral girdles. Metanephridia are excretory structures found in annelids and some other invertebrates, so they would not be expected in a vertebrate like the mystery organism. A hydrostatic skeleton is a structure found in some soft-bodied invertebrates like jellyfish and worms, but not in vertebrates, so it would also not be expected in the mystery organism. Therefore, only reduced or absent pelvic and/or pectoral girdles would be expected upon dissecting the organism.

The Following Questions Refer to the Description Below