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Which one of the following is a matching pair of a body feature and the animal possessing it?
A
Ventral central nervous system - Leech
B
Pharyngeal gill slits absent in embryo - Chamaeleon
C
Ventral heart - Scorpion
D
Post-anal tail - Octopus
Detailed Solution
Leech is an annelid, a non-chordate. In non-chordates the central nervous system is ventral, solid and double.
The leech has a nerve ring and a solid, double, mid-ventral nerve cord with ganglia. So ventral central nervous system - leech is a matching pair.
Chamaeleon is a reptile, i.e. a chordate. All chordates have pharyngeal gill slits at some stage of life, at least in the embryo, so they are not absent in its embryo.
Scorpion is an arthropod, a non-chordate; its heart is dorsal, not ventral. A ventral heart is a chordate character.
Octopus is a mollusc, a non-chordate; a post-anal tail is a chordate character and is absent in it.
So the matching pair is ventral central nervous system - leech.
The leech has a nerve ring and a solid, double, mid-ventral nerve cord with ganglia. So ventral central nervous system - leech is a matching pair.
Chamaeleon is a reptile, i.e. a chordate. All chordates have pharyngeal gill slits at some stage of life, at least in the embryo, so they are not absent in its embryo.
Scorpion is an arthropod, a non-chordate; its heart is dorsal, not ventral. A ventral heart is a chordate character.
Octopus is a mollusc, a non-chordate; a post-anal tail is a chordate character and is absent in it.
So the matching pair is ventral central nervous system - leech.