LAB ON
CRUSTACEANS
AIM: TO COMPARE EXTERNAL ANATOMY OF SOME MARINE
CRUSTACEANS AND A HORSESHOE CRAB.
MATERIALS: CRAYFISH,
SHRIMP, CRAB, COPEPOD, HORSESHOE CRAB, PROBE, FORCEPS, DISSECTING TRAY, MICROSCOPE. DO NOT BREAK UP OR CUT UP THESE
SPECIMENS...EXTERNAL ANATOMY ONLY.
PROCEDURE: EXAMINE THE 5 SPECIMENS AND DRAW AND LABEL
THE DIFFERENT PARTS LISTED BELOW.
INCLUDE SEGMENT NUMBERS WHERE NECESSARY.
DATA: YOU CAN COMPARE THE FOLLOWING, DRAWING AND
LISTING THE SEGMENT NUMBERS, PRESENCE OR ABSENCE ETC.
PART |
CRAYFISH SHRIMP CRAB
COPEPOD HORSESHOE CRAB
LEGS NUMBERS AND SKETCH ----->
CLAWS NUMBERS AND SKETCH ------>
ABDOMEN SEGMENT NUMBERS AND SKETCH ----->
CEPHALOTHORAX SIZE AND % OF BODY----->
|
Part |
Crayfish |
Shrimp |
Crab |
Copepod (Cyclops) |
Horseshoe Crab |
|
Legs and Numbers |
|
|
|
|
|
|
Claws and Numbers |
|
|
|
|
|
|
Abdomen and segment numbers |
|
|
|
|
|
|
Cephalothorax-what % of the body? |
|
|
|
|
|
ANALYSIS:
1. WHAT ARE THE SPECIAL FEATURES THAT EACH OF
THESE CRUSTACEANS HAVE WHICH ENABLE THEM TO LIVE THEIR LIFESTYLE?
2. WHICH TYPE OF BODY STYLE IS BEST DESIGNED
FOR (A) SWIMMING (B) BOTTOM LOCOMOTION (C) DEFENCE?
3. BY OBSERVING THE HORSESHOE CRAB, WHAT WOULD YOU
THINK THE TAIL IS USED FOR?
Barnacles
Barnacles
are sessile crustaceans protected by shell-like plates which enable the animals
to tolerate exposure at low tide. These
animals are filter feeders and trap fine organic particles and plankton with
six pairs of retractable feathery
cirri. Chthamalus, the small star barnacle, occurs in dense white sheets
at the top of the intertidal zone while Tetraclita
and Octomeris occur lower down the
shore. Tetraclita has the characteristic volcano shape, is grey in color
and prefers more sheltered conditions than Octomeris
which thrives on rocky shores exposed to much water movement.
Goose
barnacles encountered along the coast are associated with driftwood and ship
hulls attaching themselves to a suitable substrate by means of a long fleshy
stalk.
Examine
the diagrams below and answer the following questions.
1. In comparing the plates of the different
barnacles, using the information above, how is the plate arrangement and number
associated with the life style of each barnacle?
|
Tetracilta |
Chthamulus |
Balanus |
Octomeris |
|
4 shellplates |
6 shellplates |
6 shellplates |
8 shellplates |
|
grey |
white |
white w/stripes |
white |
|
volcano shape |
star shape |
calcareous base |
|
