There are a great many kinds of barnacles, some of which look very much like acorns, and grow to a considerable size. These are known as acorn-barnacles. And there is another, shaped rather like a piece of round tube, which burrows into the skin of whales, in which it spends all the remainder of its life! Sometimes it bores its way down so far that it actually reaches the blubber.
The young of these strange creatures pass through several transformations, just like those of the lobster and the crab. First, there is a nauplius, then a zoëa, and then a megalopa, all of which swim freely about in the water, never fastening themselves down until they are ready to pass into the perfect form.
LIFE ON THE SEA-BOTTOM.
1. Sticklebacks. 2. Carp. 3, 5, 6, 13, 17. Sea-Anemones. 4. Shrimps. 7. Prawn. 8. Fiddler Crab. 9. Starfish. 10. Sea-horses. 11. Edible Mussels. 12. Serpula Worm. 14. Hermit-Crab in Whelk's Shell. 15. Sea-urchins. 16. Rock Crab. 18. Polyzoan (Flustra). 19. Corallines (Gorgonia).
CHAPTER XXXVI
SEA-URCHINS, STARFISHES, AND SEA-CUCUMBERS
Next in order to the crustaceans comes a group of animals which live in the sea, and which are known as echinoderms, which simply means spiny-skins. This group includes the sea-urchins, the starfishes, and the sea-cucumbers.
Sea-Urchins