Mrs. Renaghan's 3rd Grade Class

Question
Are female crayfish the same as males?
Answer
No, male and female crayfish are not the same. Males have modified swimmerets (the small leglike appendages under the tail) that are white-tipped and lay between the last pair of walking legs. The females have longer, softer-looking swimmerets (for hold the eggs) and a little white pore centered between the walking legs.



Question
Do crayfish have ears?
Answer
Crayfish do not have ears, but they can hear. Equipped with thousands of sensory bristles, some sensitive to chemicals and the others to touch, crayfish can smell, feel, and hear acutely, even though they are completely covered in a hard shell.



Question
Do crayfish have to eat elodea? How many species of them are there?
Answer
Crayfish do not have to eat elodea; they eat whatever they want. Crayfish are omnivorous which means they can eat both plants and animals.

Crayfish, also called crawfish or crawdads, are closely related to the lobster. More than half of the more than 500 species occur in North America, particularly Kentucky (Mammoth Cave) and Louisiana in the Mississippi basin.



Question
How big do crayfish get?
Answer
Crayfish are usually about 7.5 cm (3 inches) long Among the smallest is the 2.5-centimetre-long Cambarellus diminutus of the south-eastern United States. Among the largest is Astacopsis gouldi of Tasmania; its length may reach 40 cm and its weight about 3.5 kg (8 pounds).



Question
How do crayfish die?
Answer
Most crayfish live short lives, usually less than two years. As with all animals, crayfish need food, water, and shelter. They die from lack of any of those or from old age.



Question
How many babies can a crayfish have?
Answer
Some time after mating the female lays about 200 eggs, which she carries in a mass under her tail. After several weeks the eggs hatch, and a hoard of minute, perfectly formed, ravenous baby crayfish emerge. At first they continue to ride along under the female's tail, eating tiny waterborne bits of food, but soon they leave this security and head out on their own. During these early days many are eaten by fish, insects, and other crayfish, but some always survive to fulfill their destiny.



Question
How many legs does a crayfish have?
Answer
You can´t tell it from the pictures of the crayfish on FOSSWEB, but a crayfish has lots of legs—depending on what you call “legs.” The thorax (middle section) has four pairs of walking legs. Crayfish also own one pair of claw-bearing legs that it extends in front of its body while moving. These strong pinchers are for cutting, capturing food, attack, and defence. The crayfish also has several pairs of specialised food handling legs, bailers to cycle water over the gills, and five pairs of swimmerets which are under the abdomen. All of these legs can regenerate if they are broken off.



Question
How many times can a crayfish shed its shell in a year?
Answer
Crayfish have a hard outside skeleton called an exoskeleton. The exoskeleton provides protection and allows movement, but doesn't allow the crayfish to grow. When a crayfish gets too big for its skeleton, it sheds it, and grows a new larger one. This is called molting. Molting occurs six to ten times during the first year when the crayfish is growing quickly, but less often in the following years.


Question
is it true that crayfish live in the sea?
Answer
Crayfish live in freshwater, like rivers, ponds, and lakes. Lobsters live in saltwater. But, in some places, the local people call lobsters crayfish. That can cause the confusion.



Question
My female crayfish laid eggs. The eggs are now hatching. Will the female die now? Do I need to separate the new babies from each other or from their mother?
Answer
The mother crayfish should be able to survive the experience. A peaceful environment with plenty of cover in or under which to hide will provide security for the mother crayfish and her babies.

When the eggs hatch it is important that there to be  lot of structure in the habitat.  Put in a bunch of plants or even plastic plants in which the babies can hide.  Rocks, pebbles, flower pots, and the like are good, too.  The thing you want is lots of places for the babies to hide from each other.  They are notorious for eating each other.  As you know, crayfish are at risk just after they have molted, and the little ones love to snack on their just molted brothers and sisters.

If you have some flake fish food, a little bit crumbled up into dust will be a good food source for the babies.  They will find the tiny bits that fall into the gravel on the floor of the habitat.

One more thing...don’t give up on the eggs.  It might be 4-6 weeks before they hatch.  You may not know when your females laid their eggs, in which case it will be a surprise when they hatch.



Question
Should male and female crayfish be kept separate in the their classroom habitats?
Answer
No, they should be kept together.  If there is a problem with aggression, you can provide more hiding places in the habitat.  When males and females are allowed to live together, there is the possibility of mating, followed later by baby crayfish, one of the most rewarding processes of nature that students might have the opportunity to observe.



Question
What are the best room and water temperatures for crayfish?
Answer
Crayfish need ample clean, cool water and sufficient food in order to be healthy in your classroom. It is virtually impossible to get the water too cold (short of freezing), but it is easy for it to get too warm. Try to keep the temperature between 5°C (41°F) and 20°C (68°F).


Source:  http://www.fossweb.com/modules3-6/StructuresofLife/index.html