37:
386:
Zooplankton are animals that drift with the current, but many have some limited means of locomotion and have some control over the depths at which they drift. They use gas-filled sacs or accumulations of substances with low densities to provide buoyancy, or they may have structures that slow down any
346:
species, 17% of the bodyweight is liver of which 70% are lipids. Benthic rays and skates have smaller livers with lower concentrations of lipids; they are therefore denser than water and they do not swim continuously, intermittently resting on the seabed. Some fish have no buoyancy aids but use their
329:
which can be expanded or contracted as the circumstances require. A disadvantage of this method is that adjustments need to be made constantly as the water pressure varies when the fish swims higher and lower in the water column. An alternative buoyancy aid is the use of lipids, which are less dense
401:, lightweight rigid structures with cavities filled with gas, which have a specific gravity of about 0.6. This enables them to swim at varying depths. Another invertebrate that feeds on the seabed and has swimming abilities is the
799:
575:
Sedberry, George R.; Musick, John A. (December 1978). "Feeding strategies of some demersal fishes of the continental slope and rise off the Mid-Atlantic Coast of the USA".
321:
Two types of fish inhabit the demersal zone: those that are heavier than water and rest on the seabed, and those that have neutral buoyancy and remain just above the
351:
which are so angled as to give lift as they swim. The disadvantage of this is that, if they stop swimming, the fish sink, and they cannot hover, or swim backwards.
545:
789:
276:, which begins between depths of roughly 200 and 1,000 m (700 and 3,300 ft) and extends to the ocean depths, where no light penetrates.
794:
761:
216:
815:
784:
751:
520:
481:
1190:
553:
209:
725:
318:) is predominantly a pelagic species but forms large aggregations near the seabed when it spawns on banks of gravel.
674:
1107:
841:
1154:
549:
440:
202:
820:
683:
387:
passive descent. Where the adult, benthic organism is limited to life in a certain range of depths, their
1061:
746:
461:
1066:
756:
512:
42:
1164:
1076:
335:
1086:
577:
54:
1071:
614:
112:
343:
268:
Being just above the ocean floor, the demersal zone is variable in depth and can be part of the
121:
504:
1056:
457:
612:
Power, James H. (May 1989). "Sink or Swim: Growth
Dynamics and Zooplankton Hydromechanics".
1169:
1149:
1091:
1051:
1046:
667:
500:
8:
1122:
963:
779:
322:
470:
Marine Policy and
Economics: A Derivative of Encyclopedia of Ocean Sciences, 2nd Edition
990:
980:
639:
631:
594:
1159:
1081:
1010:
1000:
923:
526:
516:
477:
436:
170:
98:
643:
598:
1020:
623:
586:
311:
995:
985:
888:
660:
652:
190:
126:
83:
78:
68:
1036:
1015:
1005:
262:
28:
334:, commonly found in shark livers, has a specific gravity of just 0.86. In the
1184:
883:
846:
730:
465:
428:
348:
303:
285:
63:
20:
1041:
918:
913:
908:
363:
326:
307:
295:
291:
273:
258:
246:
185:
147:
142:
103:
325:. In many species of fish, neutral buoyancy is maintained by a gas-filled
898:
355:
269:
88:
1127:
903:
635:
590:
398:
394:
374:, eating the dead remains of plants or animals, while still others are
93:
405:, which stores gas in its chambers and adjusts its buoyancy by use of
359:
1117:
1112:
928:
375:
371:
367:
272:
where light can penetrate, and photosynthetic organisms grow, or the
175:
391:
need to optimise their chances of settling on a suitable substrate.
949:
893:
856:
627:
473:
402:
331:
165:
46:
851:
406:
254:
73:
530:
825:
715:
250:
156:
720:
691:
388:
370:(invertebrates that burrow beneath the seafloor). Others are
238:
354:
Demersal fish have various feeding strategies; many feed on
878:
358:
or organisms or algae on the seabed; some of these feed on
242:
36:
16:
Part of the water column near to the seabed and the benthos
234:
290:
The distinction between demersal species of fish and
366:
on top of the seafloor), while others specialise on
682:
1182:
45:lives in the demersal zone on or just above the
499:
427:
574:
397:are able to adjust their buoyancy using their
668:
509:Animal Physiology: Adaptation and Environment
210:
249:near to (and significantly affected by) the
816:Mediterranean forests, woodlands, and scrub
675:
661:
217:
203:
495:
493:
423:
421:
568:
455:
1183:
490:
418:
257:. The demersal zone is just above the
19:Further information on this zone:
656:
611:
449:
800:Grasslands, savannas, and shrublands
762:Grasslands, savannas, and shrublands
433:Deep-Sea Demersal Fish and Fisheries
306:, but can also be found in the open
13:
543:
14:
1202:
726:Montane grasslands and shrublands
505:"Movement, Muscle, Biomechanics"
381:
261:and forms a layer of the larger
245:) consisting of the part of the
35:
842:Flooded grasslands and savannas
431:; Haedrich, Richard L. (1997).
1155:Ecological land classification
684:Biogeographic regionalisations
605:
550:University of Alaska Fairbanks
537:
1:
412:
294:is not always clear cut. The
821:Deserts and xeric shrublands
409:, pumping water in and out.
7:
1191:Oceanographical terminology
1062:Temperate Northern Atlantic
752:Broadleaf and mixed forests
10:
1207:
1165:Vegetation classifications
1067:Temperate Northern Pacific
513:Cambridge University Press
283:
43:bluespotted ribbontail ray
18:
1142:
1100:
1077:Temperate Southern Africa
1029:
973:
962:
942:
869:
834:
808:
770:
739:
708:
699:
690:
435:. Springer. p. 296.
336:velvet belly lanternshark
1087:Tropical Eastern Pacific
1037:Antarctic/Southern Ocean
458:"Wild-harvest Fisheries"
1108:Biogeographic provinces
1072:Temperate South America
790:Moist broadleaf forests
615:The American Naturalist
460:. In Hoagland, Porter;
279:
1170:Zoogeographic regions
1128:Global 200 ecoregions
1057:Temperate Australasia
795:Dry broadleaf forests
501:Schmidt-Nielsen, Knut
1150:Altitudinal zonation
1092:Western Indo-Pacific
1052:Eastern Indo-Pacific
1047:Central Indo-Pacific
515:. pp. 445–450.
464:; Thorpe, Steve A.;
456:Brander, K. (2010).
1123:Lists of ecoregions
780:Tropical rainforest
233:is the part of the
1160:Floristic kingdoms
924:Hydrothermal vents
785:Coniferous forests
747:Coniferous forests
591:10.1007/BF00390900
511:(Fifth ed.).
171:Hydrothermal vents
122:Surface microlayer
1178:
1177:
1138:
1137:
1082:Tropical Atlantic
958:
957:
865:
864:
757:Deciduous forests
522:978-0-521-57098-5
483:978-0-08-096481-2
466:Turekian, Karl K.
429:Merrett, Nigel R.
340:Etmopterus spinax
227:
226:
99:Continental shelf
1198:
971:
970:
706:
705:
697:
696:
677:
670:
663:
654:
653:
648:
647:
609:
603:
602:
572:
566:
565:
563:
561:
556:on 21 April 2016
552:. Archived from
541:
535:
534:
497:
488:
487:
453:
447:
446:
425:
312:Atlantic herring
219:
212:
205:
84:Seagrass meadows
79:Mangrove forests
55:Coastal habitats
39:
25:
24:
1206:
1205:
1201:
1200:
1199:
1197:
1196:
1195:
1181:
1180:
1179:
1174:
1134:
1096:
1025:
965:
954:
950:Endolithic zone
938:
871:
861:
830:
804:
772:
766:
735:
701:
686:
681:
651:
610:
606:
573:
569:
559:
557:
544:Newman, David.
542:
538:
523:
498:
491:
484:
462:Steele, John H.
454:
450:
443:
426:
419:
415:
384:
316:Clupea harengus
302:) is a typical
292:pelagic species
288:
282:
223:
191:Marine sediment
127:Epipelagic zone
69:Intertidal zone
49:
29:Marine habitats
23:
17:
12:
11:
5:
1204:
1194:
1193:
1176:
1175:
1173:
1172:
1167:
1162:
1157:
1152:
1146:
1144:
1140:
1139:
1136:
1135:
1133:
1132:
1131:
1130:
1125:
1115:
1110:
1104:
1102:
1098:
1097:
1095:
1094:
1089:
1084:
1079:
1074:
1069:
1064:
1059:
1054:
1049:
1044:
1039:
1033:
1031:
1027:
1026:
1024:
1023:
1018:
1013:
1008:
1003:
998:
993:
988:
983:
977:
975:
968:
964:Biogeographic
960:
959:
956:
955:
953:
952:
946:
944:
940:
939:
937:
936:
931:
926:
921:
916:
911:
906:
901:
896:
891:
886:
881:
875:
873:
867:
866:
863:
862:
860:
859:
854:
849:
844:
838:
836:
832:
831:
829:
828:
823:
818:
812:
810:
806:
805:
803:
802:
797:
792:
787:
782:
776:
774:
768:
767:
765:
764:
759:
754:
749:
743:
741:
737:
736:
734:
733:
728:
723:
718:
712:
710:
703:
694:
688:
687:
680:
679:
672:
665:
657:
650:
649:
628:10.1086/284946
622:(5): 706–721.
604:
585:(4): 357–375.
578:Marine Biology
567:
536:
521:
489:
482:
476:. p. 91.
448:
441:
416:
414:
411:
383:
380:
284:Main article:
281:
278:
263:profundal zone
225:
224:
222:
221:
214:
207:
199:
196:
195:
194:
193:
188:
183:
178:
173:
168:
160:
159:
153:
152:
151:
150:
145:
137:
136:
132:
131:
130:
129:
124:
116:
115:
109:
108:
107:
106:
101:
96:
91:
86:
81:
76:
71:
66:
58:
57:
51:
50:
40:
32:
31:
15:
9:
6:
4:
3:
2:
1203:
1192:
1189:
1188:
1186:
1171:
1168:
1166:
1163:
1161:
1158:
1156:
1153:
1151:
1148:
1147:
1145:
1141:
1129:
1126:
1124:
1121:
1120:
1119:
1116:
1114:
1111:
1109:
1106:
1105:
1103:
1099:
1093:
1090:
1088:
1085:
1083:
1080:
1078:
1075:
1073:
1070:
1068:
1065:
1063:
1060:
1058:
1055:
1053:
1050:
1048:
1045:
1043:
1040:
1038:
1035:
1034:
1032:
1028:
1022:
1019:
1017:
1014:
1012:
1009:
1007:
1004:
1002:
999:
997:
994:
992:
989:
987:
984:
982:
979:
978:
976:
972:
969:
967:
961:
951:
948:
947:
945:
941:
935:
934:Demersal zone
932:
930:
927:
925:
922:
920:
917:
915:
912:
910:
907:
905:
902:
900:
897:
895:
892:
890:
887:
885:
882:
880:
877:
876:
874:
868:
858:
855:
853:
850:
848:
845:
843:
840:
839:
837:
833:
827:
824:
822:
819:
817:
814:
813:
811:
807:
801:
798:
796:
793:
791:
788:
786:
783:
781:
778:
777:
775:
769:
763:
760:
758:
755:
753:
750:
748:
745:
744:
742:
738:
732:
731:Alpine tundra
729:
727:
724:
722:
719:
717:
714:
713:
711:
709:Polar/montane
707:
704:
698:
695:
693:
689:
685:
678:
673:
671:
666:
664:
659:
658:
655:
645:
641:
637:
633:
629:
625:
621:
617:
616:
608:
600:
596:
592:
588:
584:
580:
579:
571:
555:
551:
547:
540:
532:
528:
524:
518:
514:
510:
506:
502:
496:
494:
485:
479:
475:
471:
467:
463:
459:
452:
444:
438:
434:
430:
424:
422:
417:
410:
408:
404:
400:
396:
392:
390:
382:Invertebrates
379:
377:
373:
369:
365:
364:invertebrates
361:
357:
352:
350:
349:pectoral fins
345:
344:benthopelagic
341:
337:
333:
328:
324:
319:
317:
313:
309:
305:
304:demersal fish
301:
297:
293:
287:
286:Demersal fish
277:
275:
271:
266:
264:
260:
256:
252:
248:
244:
240:
236:
232:
231:demersal zone
220:
215:
213:
208:
206:
201:
200:
198:
197:
192:
189:
187:
184:
182:
181:Demersal zone
179:
177:
174:
172:
169:
167:
164:
163:
162:
161:
158:
155:
154:
149:
146:
144:
141:
140:
139:
138:
134:
133:
128:
125:
123:
120:
119:
118:
117:
114:
113:Ocean surface
111:
110:
105:
102:
100:
97:
95:
92:
90:
87:
85:
82:
80:
77:
75:
72:
70:
67:
65:
64:Littoral zone
62:
61:
60:
59:
56:
53:
52:
48:
44:
38:
34:
33:
30:
27:
26:
22:
21:Demersal fish
1101:Subdivisions
991:Australasian
981:Afrotropical
943:Other biomes
933:
919:Benthic zone
914:Pelagic zone
909:Neritic zone
899:Kelp forests
771:Tropical and
619:
613:
607:
582:
576:
570:
558:. Retrieved
554:the original
539:
508:
469:
451:
432:
393:
385:
353:
339:
327:swim bladder
320:
315:
308:water column
300:Gadus morhua
299:
296:Atlantic cod
289:
274:aphotic zone
267:
259:benthic zone
247:water column
230:
228:
186:Benthic zone
180:
148:Oceanic zone
143:Pelagic zone
104:Neritic zone
89:Kelp forests
1011:Neotropical
1001:Indomalayan
974:Terrestrial
904:Coral reefs
773:subtropical
700:Terrestrial
399:cuttlebones
356:zooplankton
330:than water—
270:photic zone
94:Coral reefs
1118:Ecoregions
1113:Bioregions
1021:Palearctic
929:Cold seeps
889:Intertidal
546:"Buoyancy"
442:0412394103
413:References
395:Cuttlefish
372:scavengers
310:, and the
176:Cold seeps
135:Open ocean
996:Holarctic
986:Antarctic
894:Mangroves
740:Temperate
376:predators
323:substrate
241:(or deep
166:Seamounts
157:Sea floor
74:Estuaries
1185:Category
1143:See also
1016:Oceanian
1006:Nearctic
884:Littoral
857:Mangrove
847:Riparian
644:85323978
599:83608467
531:96039295
503:(1997).
474:Elsevier
468:(eds.).
403:nautilus
360:epifauna
332:squalene
253:and the
47:seafloor
870:Aquatic
852:Wetland
636:2462076
407:osmosis
368:infauna
255:benthos
1042:Arctic
1030:Marine
966:realms
872:biomes
826:Steppe
716:Tundra
702:biomes
692:Biomes
642:
634:
597:
560:5 July
529:
519:
480:
439:
389:larvae
251:seabed
721:Taiga
640:S2CID
632:JSTOR
595:S2CID
342:), a
239:ocean
41:This
879:Pond
562:2016
527:LCCN
517:ISBN
478:ISBN
437:ISBN
280:Fish
243:lake
229:The
835:Wet
809:Dry
624:doi
620:133
587:doi
237:or
235:sea
1187::
638:.
630:.
618:.
593:.
583:44
581:.
548:.
525:.
507:.
492:^
472:.
420:^
378:.
265:.
676:e
669:t
662:v
646:.
626::
601:.
589::
564:.
533:.
486:.
445:.
362:(
338:(
314:(
298:(
218:e
211:t
204:v
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
