FOOD OF MARINE BABY FISH

Marine baby fish eat a variety of invertebrate animals. When they start to eat, after absorbing their yolk materials, they eat small organisms such as trochophores, pluteuses, dinoflagellates, copepod nauplii, fish eggs and others. As they grow, they eat larger invertebrate and vertebrate organisms. When baby fish are large enough, they eat other baby fish and then gradually develop innate food habits of their particular species. Below are examples of several food items of baby fish within the marine environment.
Figure 1) Cyclopoid copepods live in all parts of the oceans; some are planktonic and others live along the bottom. Also, some are restricted to the continental shelf (neritic species) and others to areas far from shore (oceanic species). Cyclopoid copepods seize their food with their grasping arms and mouth parts and eat it. The cyclopoid specimen, shown above, is in the genus Oithona.
Figure 2) Calanoid copepods live in all parts of the oceans; some are planktonic and others live on the bottom. Also, some are restricted to the continental shelf (neritic species) and others to areas far from shore (oceanic species). Calanoid copepods are mainly filter feeders for particles of food are brought into their mouths with currents of water created by their moving mouth parts. The calanoid specimen, shown above, is in the genus Calanus.
Figure 3) Arrowworms or Chaetognatha are found mainly in warm-water, upper– planktonic zones of the oceans. Some are restricted to the continental shelf (neritic species) and others to areas far from shore (oceanic species). Arrowworms are mostly carnivorous, capturing their prey with their mouth and teeth. The chaetognath specimen, shown above, is in the genus Sagitta.
 
 
Figure 4) There are a few polychaete worms that are planktonic and are moved around by water currents in the oceans. They are preyed upon by many species of baby fish. Polychaete worms start out as trochophore larvae (see below) after hatching from eggs. The planktonic polychaete, shown above, is in the genus Tomopteris.
Figure 5) There are a few Heteropod snails that are planktonic and are moved around by water currents in the oceans. They are preyed upon by many species of baby fish. Heteropod snails start out as trochophore larvae (see below) after hatching from eggs.The free-swimming pelagic heteropod, shown above, is in the genus Cariniaria.
Figure 6) Crabs in the order Decapoda are short-tailed members. A zoea, shown above, is the first of several larval stages of crabs. Many marine crabs go through different larval stages after hatching from eggs. These larval stages are found in large swarms mainly along the continental shelf where crabs live and reproduce.
 
 
Figure 7) The post-hatching larval forms of many polychaete worms are pear- or top–shaped tiny organisms, named a trochophore, with 2 rings of ciia and a dorsal eyespot. In some species this stage is found in the egg, and the larva has no opportunity for a free-swimming existence.The free- swimming pelagic trochophore, shown above, is in the genus Polygordius.
Figure 8) The post-hatching larval forms of many sea stars, asteroid sea stars, are tiny bilateral barrel– shaped organisms, named bipinnaria, with 2 or more bands of ciia. These bands of cilia are for locomotion. After a few weeks of free swimming, three additional lobes develop at the anterior end, and the larva is then termed a brachiolaria. The free- swimming pelagic bipinnaria, shown above, is in the genus Asterias.
Figure 9) The post-hatching larval forms of many sea urchins, echinoids, are tiny bilateral easel– shaped organisms, named an echinopluteus, with 4 to 6 long arms. The echinopluteus larva is small and free-swimming and full development into a mature sea urchin takes months. The free-swimming pelagic echinopluteus, shown above, is in the genus Arbacia.