Crustaceans (1955)

since the beginning of History the Waters of the Earth have provided an inexhaustible supply of food and a livelihood for much of mankind and not the least of the fishermen who daily unload their countless tons of Seafoods at Ducks around the world are those who find crustations as profitable a hall as fish shrimp fishing for one example is Big Industry wherever edible shrimp are found Crustaceans or crustacea form an important class of animals that belong to the largest film in the animal kingdom the arthropoda or joint footed invertebrates animals without backbones they are related to spiders scorpions insects millipedes and all invertebrates which have jointed appendages the crustacea likee trilobites which lived millions of years ago are well-known prehistoric relatives abundant fossil remains show that the trilobites had segmented bodies and simple jointed appendages similar to Modern crustations but modern crustations have a wide variety of specialized appendages adapted to the particular needs of each species such as digging Burrows feeding offense and defense and many kinds of locomotion a hard crusty shell or exoskeleton encloses their segmented bodies and gives the crustations their name while nicknamed insects of the sea they also live on land and in freshwater they breathe through gills or general body surfaces most crustacea have two pairs of antenni from the wide variety of crustacea microscopic to immense in size we shall observe in this film Representative members of the class each early spring as if by Magic temporary rainwater ponds in eastern North America suddenly team with a delicate crustacea less than an inch long the fairy shrimp their scientific name branchiopoda refers to their branch legs by which they Propel themselves around usually on their backs they also breathe through their legs which keep a constant current of water flowing past them for supplies of food and oxygen the male has an enlarged second pair of antenna which serve as claspers to hold the female during mating this female has laid eggs she is carrying them around in an egg pouch the fairy shrimp die and the eggs sink to the mud at the bottom when the temporary rainwater Pond dries up neither the hot summer sun nor the winter freezes harm them a new generation recurs within 2 days after rains flood the pond again a second kind of crustacea the asrat are being studied in this research laboratory a close look reveals that this tiny crustacean's body is not segmented it is covered by a b valve shell which is hinged along the back when the shell is open the animal can extend its appendages to propel itself rapidly through the water Cyprus reproduced by parthenogenesis females lay eggs from which only females hatch no males are known to exist Cyprus live in fresh and salt water and feed on decaying vegetation these men are dragging a special kind of net behind a boat to collect some of the minute plant and animal organisms known as Plankton which drift about in bodies of fresh and salt water many of the animal forms of plankton are crustacea called copepoda after their or shaped legs Plankton is of tremendous importance to life in the sea though microscopic in size it is so plentiful that it is the diet of some whales many small fish eat it and in turn are food for larger fish and other animals commercial fishermen search for areas rich in Plankton since great numbers of fish feed in such areas here is a Sapp of the wide variety of almost transparent tiny animals collected by the Plankton net this little freshwater copap pod Cyclops has only one eye centered on its head in all of the oceans of the world the cedia or well-known Barnacles are found the rock Barnacles living on these rocks are born free swimming but they soon fasten themselves by appendages to a permanent moing once fastened they stay for Life a shell called a carapus encloses the barnicle's body and legs when covered by water their shells open and six pairs of branched legs come out to pull minute organisms into the mouth thousands of barnacles make crowd a single square foot of rock countless Crustaceans like Barnacles and planktonic animals are constantly filtering the minute animals and plants from the waters in which they live they then themselves become food for larger organisms the malacria are a fifth type of crustacea they include a few land forms that live in damp places such as truck Gardens or under rotting logs like other crustacea The Familiar sa buug breathes through gills decayed vegetation is its Chief food sa bugs are little larger than ants but sometimes large numbers of them attack the tender leaves of young plants causing considerable damage poisons must then be used to destroy them about 6,000 species of Malik castria include the crabs and shrimp and the other large animals in the class crustacea the lobsters and crayfish all all of these have 10 walking legs and are thus called decapods so many lobsters are caught for food in countries around the world that few live long enough to attain full size but some do grow as long as 2 ft and weigh over 30 lb Lobster meat is one of the tastiest Seafoods many crabs are edible too such as the blue crab of Atlantic Coast the hermit crab lives in borrowed shells which it trades for larger sizes as it grows the fiddler crabs have only one enlarged claw which they wave about in an amusing manner the crayfish or crawfish is abundant in freshwater bodies swamps and streams we have transferred this colorful species from its muddy Habitat to a clear water setup for better observation the crayfish has two distinct body regions a jointed abdominal region or tailand and a rigid SEO thorax or head end its tail often serves as a paddle for a quick getaway the crayfish is much like the lobster only smaller its entire body is covered by a hard exoskeleton its long antenna are sensitive to touch and taste each compound eye mounted at the end of a movable stalk consists of hundreds of smaller eyes the eyes are especially adapted to detect moving objects beneath the protecting exoskeleton are the Gill Chambers through which the crayfish pumps water to obtain oxygen some of the gills are attached to certain appendages which assist in the breathing process large powerful claws help the crayfish defend itself and are also used in attack on occasions crayfish May attack one another in such encounters serious injuries are often inflicted the claws can cut and Crush almost any body part this one has suffered a badly wounded leg a serious injury for most animals but look a marvelous process called autotomy enables the crayfish to sever the wounded leg voluntarily between certain segments leaving only a stump autotomy stops the bleeding automatically after several months of gradual ual development wonderfully a new leg of full size will finally replace the injured one amazing too is the life cycle of the crayfish after The Mating Season the female lays eggs which are fastened to her swimmeret appendages by a glue she secretes the egg cluster so resembles a Blackberry that females with eggs are said to be in Berry the female moves her swimmeret appendages back and forth in the water to aate the eggs here is another species in Berry over a period of several weeks the eggs develop and hatch the young crayfish cling to the mother swimmer rettes for a few days after hatching as their bodies grow the hard exoskeleton cannot expand so it is shed by molting and replaced by a new and larger one molting occurs about seven times the first year and once or twice a year thereafter malacostraca means soft shelled but refers only to the softness of the shell immediately following the shedding of the exoskeleton since the shells of malacostracans include the hardest shells of all Crustaceans now watch the crayfish make the final flip out of its old skeleton until the new exoskeleton hardens hours later Crustaceans are helpless against attack the crayfish eats both vegetable and animal matter Dead or Alive the claws are sometimes used to capture and tear the food but the smaller appendages are used to hold the pieces of food which are torn up by the jaws and swallowed a group of teeth in the stomach called the gastric Mill grind the food into fine particles while crayfish cause considerable damage at times by eating cultivated crops or by destroying Lawns and levies with their Burrows the damage is small compared to the value of the thousands of tons of crayfish consumed annually as food without the Crustaceans the animal kingdom would have a very different appearance these animals that abound in such great variety are fascinating to man they provide the Delight of many tasty seafood dishes and in some measure contribute even to the clean beauty of the waves that wash our Ocean Shores