In the picture you see a star-fish with the thin, crooked rays, or arms. He is called a sand-star, because he likes to lie close to the sand on the sea-bottom. He is of a sand color.
The one with the curled arms, like plumes, is called the brittle-star. That is because he breaks so easily. He is a very queer fellow. When things do not please him, he drops all to pieces. It would be a queer thing, if, when you feel cross or afraid, you could throw yourself down and fly to pieces, jerking off your head, your arms, and your legs!
You have heard how crabs can drop off a claw, and then another grows out. You also know that a spider does not mind much about losing a leg or two. These facts cause us to feel sure that these creatures do not suffer pain at the loss of a part of their bodies. If the loss of legs, claws, or rays caused pain, these animals would not be so ready to drop them.
There is no other creature that breaks itself so readily and so entirely as the brittle-star. It will throw off all its rays, and they will float away in many directions, while the little disk is left alone to sink or to float.
When the star-fish loses one or more, or even four rays, others will soon grow. All the animals of this family renew lost parts even more easily than crabs do.
It is very hard to get a brittle-star out of the water. As soon as it feels a net or scoop or the upper air about it, or a pail of fresh water rising gently around it, it breaks into many pieces.
On the end of every ray is a little sharp eye. When you frighten Mr. Brittle-Star, off swim his legs, every one by itself, and each has its one eye to look out for it. I never saw anything else so queer; did you?
The strong, prim-looking star-fish, with five points, is called the cross-star. It is the common, or pattern star-fish. There are many other kinds. I will tell you in the next lesson of one very pretty kind. You must go to larger books to learn all that is known about these strange and lovely creatures.
We will look at the model, or cross-star. Turn the animal over. The mouth is in the centre of the under side. Do you not find there is a seam, or groove of the hard skin, all the way down the centre of each ray? From the mouth a nerve runs down to the point of each of the rays.
Along the centres of the under openings in the rays are set very, very many little blunt points. These points are like tiny tubes close together. It is on these that the star-fish can walk or creep on the bottom of the sea, or over rocks. The star-fish seek their food as they crawl slowly about.