Which one of the following groups of three animals each is correctly matched with their one characteristic morphological feature?
- array|l|l| Animals & Morphological features \ Scorpion, spider, cockroach & ventral solid central nervous system \ array
- array|l|l| Animals & Morphological features \ Cockroach, locust, Taenia & metameric segmentation \ array
- array|l|l| Animals & Morphological features \ Liver fluke, sea anemone, sea cucumber & bilateral symmetry \ array
- array|l|l| Animals & Morphological features \ Centipede, prawn, sea urchin & jointed appendages \ array
Answer
(1) array|l|l| Animals & Morphological features \ Scorpion, spider, cockroach & ventral solid central nervous system \ array
Solution
Scorpion, spider and cockroach are arthropods, and arthropods have a ventral, solid (non-tubular), double nerve cord, i.e., a ventral solid central nervous system. Hence (1) is correct.
Taenia (tapeworm) is a platyhelminth whose body is not metamerically segmented (its proglottids are not true segments), so (2) is wrong.
Sea anemone (cnidarian) is radially symmetrical and so is the adult sea cucumber (echinoderm), so (3) is wrong.
Sea urchin is an echinoderm without jointed appendages, so (4) is wrong.
Answer: (1)