Animal Parasites and Messmates

abdomen abode acarus amphipod animal annelids appearance Ascaris assistance attacks become birds blood body Bothriocephalus Caligi carapace caterpillar cavity cercaria cestode cetacea ciliated cirrhipedes coast colour completely crab creatures crèche crustaceans curious cysticerci cysticercus damp earth distome echinoderm eggs embryos enclosed encysted establish evolution female fish fleas gasteropod genus gives lodging harbours hatched hermaphrodite hooks host hymenoptera ichneumons Illustrations infested inhabit insects intestines introduced isopod kind known larva larvæ leeches Leuckart live male manner messmates microscopic midst molluscs Mons mother mouth Müller natural naturalists neighbour nematode nourishment observed organs pagurus parasites pass peritoneum pinnotheres plants polyps prey produce Professor Semper progeny remarkable resemble scolex seek sexes sexual sheep shell shelter side skin sometimes species sponge stomach Strongylus studied sucker tænia tæniæ Tania tape-worm trematode trichinæ usually whale worms young