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the most complex group of invertebrate is cnidarians
The largest gland is liver and most complex organ is brain .
Phylum Vertebrata has the most complex animals.
Knee
Insects are the largest and most common invertebrate group.
The Arthropods are the largest and most diverse.
the biosphere
The cerebrum is the largest and most complex part of the human brain.
Segmented Worms
The Brian
It is Insecta.The largest group of arthropods are aquatic, so things like shrimp, lobster, (and the most popular) Crab.Crab is the largest group in the arthropods.