. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. DIGESTIVE ENZYMES IN SIX CRABS 41 (A) 0025 - — 0015 ^ 0010 - 'E 3. • £ .> 0 000 0 045- T I I 1 (B) u 1C 0 40 - '5 g. 035- OT • 025 • 0,20 • 015 • I 1 010 - 005 - 000 - n T x I — x — Int Por Flag Species Figure 4. Specific activity of (A) /3-glucosidase and (B) laminarinase measured from crude digestive gland extract of six crab species with different feeding habits. Values are mean (units mg~') ± , where units are in /imol p-nitrophenol rnin"1 for /3-glucosidase and in , glucose
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. DIGESTIVE ENZYMES IN SIX CRABS 41 (A) 0025 - — 0015 ^ 0010 - 'E 3. • £ .> 0 000 0 045- T I I 1 (B) u 1C 0 40 - '5 g. 035- OT • 025 • 0,20 • 015 • I 1 010 - 005 - 000 - n T x I — x — Int Por Flag Species Figure 4. Specific activity of (A) /3-glucosidase and (B) laminarinase measured from crude digestive gland extract of six crab species with different feeding habits. Values are mean (units mg~') ± , where units are in /imol p-nitrophenol rnin"1 for /3-glucosidase and in , glucose min~' for laminarinase. Key to crab species: Int = Nectocarcinus integri- fons (n = 5), Por = Pelrolisthes elongatus (n = 5), Lep = Leptograpsus variegatus (n = 5), Velv = Nectocarcinus tuberculosus (n = 10), Eur = Carcinus maenas (n = 5), Flag = Plagusia chabnts (n = 5). chabrus collected in this study were similar to those ob- served by Edgar (2000). In both studies, crabs were sampled subtidally from exposed reef in 3-5 m of water. In contrast, the majority (72%) of P. chabrus captured by Griffin (1971) were collected from exposed rocky platforms in the inter- tidal zone where red and coralline algae are more common. The greater abundance of these algae may make them a more attractive food source or more likely to be incidentally ingested. Reflecting its carnivorous nature, P. chabrus displayed high protease and trypsin activity, and it was this high activity of protease and trypsin that separated P. chabrus from the other crab species in the MANOVA. P. chabrus had the highest trypsin activity encountered in any of the species studied. The trypsin activity was similar in value to that of the slipper lobster, Themis orientalis ( units mg~'), and the karuma prawn, Penaeus japonic-its ( units mg~'), two species whose diets also contain consid- erable amounts of protein (Maugle, 1982; Johnston and Yellowlees, 1998) (Table 2). The low plant content in th
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
