As a general rule,

in red-blooded animals furnished with feet
and not oviparous, the male is larger and longer-lived than the female
(except with the mule, where the female is longer-lived and bigger
than the male); whereas in oviparous and vermiparous creatures, as
in fishes and in insects, the female is larger than the male; as,
for instance, with the serpent, the phalangium or venom-spider, the
gecko, and the frog. The same difference in size of the sexes is found
in fishes, as, for instance, in the smaller cartilaginous fishes, in
the greater part of the gregarious species, and in all that live in
and about rocks.