40 INVERTEBRATES. POLYPS, WORMS 



In Alcove 3 arc shown coral animals and their relatives: plant-like 



hydroidfl which often arc mistaken for sea moss, hut which 

 Alcove \ 

 p really are a series of polyps living in a colony; jellyfishes 



with their umbrella-shaped bodies and long streaming 



tentacles; brilliant colored sea anemones, sea fans and sea plumes; the 



magenta colored organ-pipe coral, the stony corals, and the precious coral 

 of commerce. Coral polyps mistakenly called "coral insects" are the 

 animals that build up the coral reefs. In front of the window is a life-sized 

 model in glass of the beautiful Portuguese Man-of-YYar. This organism 

 is really a colony of many polyp Individuals attached to one another, and 

 specialized for various functions. 



The best known species in this group is the tapeworm, whose develop- 

 ment and structure are accurately shown by the models in 



__, . the central ease. As w ill be seen, its structure is more com- 



Flatworms 



plex than that of preceding forms. 



These are for the most part parasitic, living in the diges- 



„ tive canals of mammals. The most familiar is the common 



Roundworms 



roundworm or intestine worm, Ascari.s, an enlarged model of 



which is exhibited. 



The minute wheel animalcules comprise many exquisite and grotesque 



forms, some of which construct tubes of gelatinous substance, 



^ ., sand-grains, etc. A few 7 of the species are parasites, but 



most of them live a free, active life. They are aquatic and 



mainly found in fresh water. 



The sea-mats in Alcove 7 are plant-like animals which lead the colonial 



form of life. The majority of the species are marine, al- 

 Alcove 7 

 c . though a few occur in fresh water. The lamp shells shown 



o63.-IT13.tS 



in this alcove superficially resemble clams, but by structure 



are more closely related to the worms and starfishes. 



Alcove 8 is occupied by the starfishes, the sea urchins, sea cucumbers 



and sea lilies. The starfish is the pest of the oyster beds 



. ~ , where it feeds on ovsters and destrovs them in large numbers, 



btsrnsn • * 



The brittle stars when handled or attacked are able to drop 

 off an arm and later regenerate another. Sea urchins are an important 

 article of food in Europe and the West Indies. 



The annelids, typified by the familiar earthworm, are worms whose 



bodies are made up of rings or segments. They are inhab- 

 . .. , itants of both fresh and salt water, many kinds living in the 



mud and sand of the shore while others bore into wood and 

 shells. The "houses" that these annelids build are often very beautiful 

 and interesting. In the window is a group showing a section of a mud fiat 

 on the New England coast with the variety of worm life found in what to 

 the casual observer seems to be an uninhabited area. 



