The Crayfish Invertebrates 
locomotion. A crayfish, on the bottom of a pond, 
seems to glide about with great ease; but place it on 
land, and it is an awkward walker. The reason for 
this difference lies, I believe, in the aid given by the 
swimmerets when the creature is in water. 
The mother crayfish has another use for her swim- 
merets; in the spring, when she is ready to lay eggs, 
she cleans off her swimmerets with her hind legs, 
covers them with waterproof glue, and then plasters 
her eggs on them in grapelike clusters of little dark 
globules. What a nice way to look after her family! 
The little ones hatch, but remain clinging thus to 
their mother until they are large enough to scuttle 
around on the brook bottom and look out for them- 
selves. 
Not only is the crayfish armed in the beginning 
with a number of legs, antenne, etc., but if it happens 
to lose any of these organs, they will grow again. It 
is said that, when attacked, it can voluntarily throw 
off one or more of its legs. We have often found one 
of these creatures with one of the front claws much 
larger than the other; it has probably lost its big 
claw in a fight, and the new growth was not yet com- 
pleted. 
I have been greatly entertained by watching a 
female crayfish make her nest in my aquarium which 
has, for her comfort, a bottom of three inches of clean 
gravel. She always commences at one side by 
thrusting down her antennz and nippers between the 
glass and stones; she seizes a pebble in each claw and 
pulls it up and in this way starts her excavation; but 
when she gets ready to carry off her load, she comes 
to the task with her tail tucked under her body, as a 
lady tucks up her skirts when she has something to 
do that requires freedom of movement. Then with 
283 
