Date:   ____________________________________

B L U E   C R A B   O B S E R V A T I O N   L A B:
Problem/Question:  what does the Blue Crab look like?

Hypothesis:  In the space below draw and label the Blue Crab:

Materials:

• Live Blue Crabs

• Lab Sheet

• Magnifying Glass

• Ruler

• Tongs for teacher to hold crab

Procedure:

  1.  First locate the following parts and place a check mark after the part when you have observed it:  (Use the diagram for help)

_____Abdomen
_____Eye Stalk
_____Claw
_____Mouth
_____Swim Paddles
_____Walking Legs

  2.  Compare the abdomens to the ones in the diagram.  Is the crab that you are observing a male or a female?
Reminder*  The female's apron will be wider than the males.  The female needs a wider apron to hold her eggs.  The females also have red tips on their claws and the male crab's claws have bright blue coloring.  The blue coloring gives the crabs their name, blue crab!

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  3.  Watch the Crab move and answer the following questions:

     What direction does it go?     _____________________________

     Does it swim and walk in the same direction? ___________________________

     How many legs doe the crab have?   _____________________________

Which legs does the crab use to do the following activities?
Remember the first pair of legs are called claws, and its last pair of legs are called swimming legs.

Walk _________________________________
Swim _________________________________
Eat   __________________________________

  4.  A "legal crab that is large enough to be kept and eaten after being caught must measure five inches across the shell from tip to tip, or three inches if it is soft (in the molting stage.)  Measure your crab.

     The length of my crab is:  ___________________________

  5.  Crabs eat a wide variety of animals including soft crabs, clams, worms, barnacles, as well as injured or weak fish, and at as scavengers by eating recently dead or decaying animals.  What part of their bodies do the Blue Crabs use for catching and eating their prey?

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 6.  Crabs spend most of their lives on the bottom of the ocean.  Can you think of any animals that a crab would not like to eat?

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 7.  In the space below, draw what a Blue Crab actually looks like and label the parts.

     8.  On the lines below list any other interesting features or movements that you observed while investigating the Blue Crab.
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Conclusion:
How does your picture in your hypothesis compare to what the actual crab looks like?
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