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Living where land and water meet: Fiddler Crabs. Materials  Prepare salt water by filling a pail with water, add drop of conditioner, add 2 pinches of.

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Presentation on theme: "Living where land and water meet: Fiddler Crabs. Materials  Prepare salt water by filling a pail with water, add drop of conditioner, add 2 pinches of."— Presentation transcript:

1 Living where land and water meet: Fiddler Crabs

2 Materials  Prepare salt water by filling a pail with water, add drop of conditioner, add 2 pinches of Instant Ocean, stir  4 ½ cups of sand mixed with 4 ½ cups of humus, mix, remove sticks  China marker  Tape  Tank with lid  Water bowl  Paper towel  Hairgrass  Cup with lid  Ruler

3 Overview  Review necessary elements of a habitat for Fiddler Crabs  Create habitat  Record living and nonliving elements in habitat  Discuss how to take care of the Fiddler Crab  Discuss feeding schedule  Observe crabs and record questions

4 Background  Along the shore of almost any body of seawater, you can spot a variety of crabs.  Crabs are crustaceans, animals whose bodies are covered by hard shells, or exoskeletons.  Crustaceans also include lobsters, crayfish, and shrimps.  Crustaceans are a subgroup of larger group of animals known as arthropods – the most abundant macroscopic animals on Earth.

5 Crustaceans  Crustaceans have segmented bodies and jointed appendages.  An appendage is any part that extends out from an animal’s body, such as legs, feelers, and mouth parts.  All crustaceans have armor-like exoskeletons with flexible joints.  Muscles inside of and attached to the exoskeleton give these animals great strenth.

6 Fiddler Crab  Most crabs live in or near the sea, either in shallow tidal mud flats or in the depths of the ocean.  Most crabs breathe with gills.  Lay eggs in a wet environment  Cold blooded  Metamorphosis in stages from egg to juvenile  Can change color  Around 4,500 kinds of crabs  62 kinds of Fiddler Crabs  Indigenous to U.S. means can be found here

7 Body Structure  2 main parts Cephalothorax (head and thorax) abdomen  Body covered by a shell called the carapace.  Attached to the cephalothorax are 2 movable stalks that support the crab’s compound eyes.  Eyes can see 360 degrees and can extend upward to see over small obstacles and to retract into a groove for protection.  They can see stationary objects that are feet away and moving figures that are 330 feet away.  2 pair of small antennae on the head – one for smell and the other for touch.  Four pairs of walking legs and 2 pinchers connected to the cephalothorax.  Walk sideways.  The female has 2 small, equal sized claws, and the male has one large claw up to twice the size of the other claw.  Use claws to feed and dig.

8 Behavior  Semiterrestrial – living part time in water and part time on land  Remain out of water by keeping a small amount of seawater in their gills.  Must return periodically to the water to renew their water supply.  If see bubbles while in the water, the crab is producing carbon dioxide as it breathes and fills its gills with seawater.  During high tide, they stay in their burrows and emerge during low tide.  Change colors – usually dark in sunlight and paler at night or when cloudy and at times will match color to environment.  Male feeds only with the small claw but digs with both.  Male uses its large claw to attract a female, discourage rivals, and defend territory.  Because the claw is white and reflects sunlight, it can be seen at a great distance.  If a large claw, which breaks easily, is lost, a new feeding claw will take its place and the new claw will grow to reach the size of the original large claw.  Produces a squeaking sound, much like a cricket, by rubbing the surfaces of its big claw against its thorax.

9 Feeding Behavior  Feed mainly at low tide.  Known as “deposit feeders,” they roam the flats of much and sand, scooping up sand and soil that contain small particles of food, mainly bacteria and algae.  Pushes sand and mud into its mouth with the small, spoon-like feeding claws.  Layers of moving mouth parts open and close like elevator doors, and spoon-like hairs separate the tiny pieces of food from the sand and mud.  After filtering out the food, it forms the sand and mud into little pellets and deposits them on the ground.  They often feed on dead fish and other creatures.

10 Survival Behavior  Hide among marsh plants and dig burrows for protection.  Dig its burrow above the tide line.  A burrow can be up to 2 feet deep.  Burrow usually houses one crab at a time.  To prevent water from entering its burrow, the fiddler lines the burrow with mud and plugs it up using the pellets at the burrow’s mouth.  At the burrow’s deepest end, the fiddler digs another few inches, creating a horizontal tunnel.  During both high tide and winter hibernation, the crab stays in the tunnel.

11 Life Cycle  Mate in the spring.  Male attracts female by waving its large claw or by drumming it against the ground at night.  Each species has a specific wave pattern that females can recognize.  Reddish, brown eggs that hatch in water.  The newly hatched babies are microscopic and undergo a series of molts before becoming pea-sized juveniles.  When young, they molt about once every 10 days; as adults, once or twice a year.  The life span is around 2 years.  After a molt, it has soft shell for about 30 minutes.

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13 What would you like to know about the Fiddler Crabs?

14 Schedule  Feeding Feed once a day at 7:40. Put food in water and on land. Remove old food before adding fresh food. Can also feed small pieces of apple, banana, or lettuce on the sand.  Water Change the water once a week. Slowly lift the water bowl, dump the water, rinse the bowl, replace the bowl in the habitat, and refill water. Important not to spill water onto the sand.  Move habitat gently.

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17  Put plankton in water and on land.  What happened when you put food in tank?  Do the crabs respond to the food the same way the frogs do?  How are the crab’s responses different?

18 Reading Selection  Read  Write 2 or 3 things you discovered about how people study dolphins.  How is the animal research you are doing similar to the dolphin research being done at the research center?  How is it different?  How is your animal log similar to the data sheet the research center is using?  How is it different?

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21 Extensions  Research other kinds of crabs and create a display.  Use a Venn diagram to compare the classroom habitat of the crab with its natural habitat.  Feed the crabs a variety of foods to discover which the crabs prefer. Experiment with tuna flakes, shrimp pieces, green vegetables, and fruits.  Crustaceans are a popular food source for humans. Research the nutritional value of crustaceans, as well as diverse ethnics dishes that use these animals.

22 The End!!!


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