248 THE BIOLOGY OF MARINE ANIMALS 



nourishment. Parasitic copepods found in fish and invertebrates usually 

 have suctorial mouth parts which allow only liquid or semiliquid food to 

 be ingested. Ectoparasitic Epicaridea possess stylet-like mandibles en- 

 closed in a suctorial oral cone. 



Pycnogonids are partially sucking, partially raptorial in habit. They are 

 armed with a complicated proboscis for sucking in soft tissues and fluids. 

 They show a preference for hydroids and anthozoans, but also attack 

 many other soft-bodied animals, including tunicates, holothurians, etc. 

 Hydranths are seized with the chelae and gradually forced into the mouth. 

 When feeding on larger animals, e.g. actinians, the proboscis is thrust into 

 the host and the tissue juices sucked out. In the hind part of the proboscis 

 there is a filter of chitinous hairs which strain out coarse matter so that 

 only juice and fine particles reach the mid gut (45). 



Finally, we may mention those endoparasites, which have lost both 

 feeding mechanisms and alimentary canal, and absorb circumambient 

 nutrient fluids through the general body surface. Examples are cestodes, 

 endoparasitic gastropods (Entoconchidae) and rhizocephalans (7). 



REFERENCES 



1. Alexander, W. B., Birds of the Ocean (London, Putnam, 1928). 



2. Al-Hussaini, A. H., "On the functional morphology of the alimentary 

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 J. Micr. ScL, 90, 109 (1949). 



3. Allen, G. M., Bats (Cambridge, Harvard Univ. Press, 1940). 



4. Anderson, J. M., "Studies on the cardiac stomach of the starfish, Asterias 

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5. Ankel, W. E., "Erwerb und Aufnahme der Nahrung bei den Gastropoden," 

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5a. Atkins, D., "The ciliary feeding mechanism of the entoproct Polyzoa, 

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6. Atkins, D., "On the ciliary mechanisms and interrelationships of lamelli- 

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la. Ballanttne, D. and Morton, J. E., "Filtering, feeding and digestion in 

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8. Barrington, E. J. W., "Observations on feeding and digestion in G/osso- 

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9. Berrill, N. J., "On the occurrence and habits of the siphonophore, Stepha- 

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10. Bidder, G. P., "The relation of the form of a sponge to its currents," 

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10tf. Broad, A. C, "The relationship between diet and larval development of 

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11. Cannon, H. G., "On the feeding mechanism of Nebalia bipes," Trans. Roy. 

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