. Beginners' Zoology . the oysters to attach themselves. The dark spot in thefleshy body of the oyster is the digestive gland,, or cut ends of the tough adductor muscles are noticeablein raw oysters. The starfish is very destructive in oysterbeds. Pearls are deposited by bivalves around some irritatingparticle that gets between the shell and the mantle. Thepearl oyster furnishes most of the pearls; sometimespearls of great value are obtained from fresh-watermussels. Namearticles that aremade partly orwholly of mother-of-pearl. Study of a LiveSnail or Slug. — Is J J I, mouth; vf, hf,
. Beginners' Zoology . the oysters to attach themselves. The dark spot in thefleshy body of the oyster is the digestive gland,, or cut ends of the tough adductor muscles are noticeablein raw oysters. The starfish is very destructive in oysterbeds. Pearls are deposited by bivalves around some irritatingparticle that gets between the shell and the mantle. Thepearl oyster furnishes most of the pearls; sometimespearls of great value are obtained from fresh-watermussels. Namearticles that aremade partly orwholly of mother-of-pearl. Study of a LiveSnail or Slug. — Is J J I, mouth; vf, hf, feelers; e, opening of egg duct; f, foot; moist ? Do land ?««, mantle; /«, opening to lung; «, vent. snails and slugs have lungs or gills? Why? How many pairsof tentacles have they? What is their relative length and position?The eyes are dark spots at bases of tentacles of snail and at tlietips of the rear tentacles of slug. Touch the tentacles. Whathappens? Do the tentacles simply stretch, or do they turn inside. Fig. 202.— A Snail. io6 BEGINNERS ZOOLOGY
Size: 2339px × 1068px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookidbeginnerszoo, bookyear1922
