A 19th century children's book: 'The Water-Babies, A Fairy Tale for a Land Baby,' written by the Reverend Charles Kingsley, was popular both in England and in the US. I remember finding it in the Daytona Beach library in the 1950's. The story's hero, a poor chimney sweep, drowned in a river but was reborn as an aquatic child, a water baby.
Image of rather cute zoea larval stage of a sand fidder crab, Uca pugilator, by Wendy B. Allen, Manager, North Inlet – Winyah Bay National Estuarine Research Reserve USC Baruch Marine Field Laboratory, Georgetown SC. Posted on Zooplankton Online, with permission.
There is an abundance of real water babies in Georgia estuaries, which is why the salt marshes, creeks, and sounds are called 'nurseries' for marine life. These babies are the young, or larvae, of many animals, including benthic and aquatic invertebrates and fish. After breeding, females release millions of fertilized eggs into coastal waters. Their larvae develop through a number of stages as they drift with the tides, eating algae and other plankton and growing until they become miniature adults. Then the former babies either settle down to a suitable bottom habitat, or swim off to join their parents in the open estuary and coastal ocean.
Although small, marine larvae can be exotically beautiful, often looking quite different from their parents. One can capture larvae from estuarine water with a plankton net (bought or home-made using instructions in an appendix of the Marsh Mud and Mummichogs book), and then view their delicate forms with a hand lens or low power microscope.
Crab larvae begin as spiny zoea as in the image above, but change to a more crab-like megalopa stage before their final transformation to tiny adults.
Other common invertebrate larvae include fuzzy early stage mollusc larvae (trochophores) and butterfly-like later stage mollusk larvae in tiny shells (veligers),
Left: Scanning electron microscope image of a 9-hour old trochophore of the marine gastropod, Haliotis asinina, sf - shell field, the beginning of the snail's shell, "Haliotis asinina trochophore" by Daniel J. Jackson, Gert Wörheide and Bernard M Degnan - Licensed under CC BY 2.0 via Wikimedia Commons -
Right: A bivalve veliger stage larva swimming, collected from a plankton tow by Charles Krebs, Issaquah, WA USA, used with permission.
Embryologists study the development of spiny sea urchin larvae for clues about how bodies emerge from a single fertilized egg to a fully functional animal.
Pluteus larval stage of a sea urchin.
By Otto Larink [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
A gallery of images of planktonic animals, including many larval forms, is posted on the website Zooplankton Online.