Pluteus, a free-swimming larval stage in the development of echinoderms, 54.
The young barnacles when hatched from the egg are free-swimming larv as with the other Crustacea.
The commonest and most thoroughly investigated form of Asteroid larva is a free-swimming form known as Bipinnaria.
The young Sacculina is an active, free-swimming larva essentially like a young prawn or crab.
Nothing could be more brilliant or varied than the hues of the free-swimming fishes.
Besides the myriads of free-swimming copepods, there are parasitic forms in great number.
Movement, free-swimming or gliding, with especial tendency to get under clumps of foreign matter.
When the eggs hatch, the free-swimming young escape from the mantle cavity.
The ancestor was consequently a small, marine, free-swimming creature.
Both sexes become mature in this free-swimming stage (Fig. 73, C, D), and impregnation is effected.