Reconsideration on Feeding Habits of Marine Pelagic Copepods (Crustacea).

Abstract

Shuhei N ishidatt Abstract The feeding ecology ofmarile pelagic copepods has been intensively studied since the 1910 ， s ． Recently ， many new techniques ， such as high − speed cinematography ， deep − sea ROV ， azad SCUBA ， have been introduced丘）r direct observatios of 出 e 三 r feeding behavior ， These have clear 正 y revealed that particle −feeders employ suspensiQn feed − ing but not filter −feeding and that appendicularian houses are 血 portant food items f（）r some pelagic calanoid ， harpacticeid ， and poe 〔 ： ilostornatoid copepods ． Part三 cle −feeders comm ． only utilize microzooplankton such as c 三 h− ates and copepod 皿 aup 正 ii and fecaf pellets ， Detrit 三 vory ， strict selec も i、 ・ e predation ， and gorging have been feund exclusively in oceanic copepods ． Five calanoid families Diaix 五 dae ， Parkiidae ， Phaenn 五 dae ， Scolecitrichidae ， a皿 d Tharybidae w 三 th spec 三 al sensory setae on the mouthpar 士 s and the poecilostomatoid Oncaea are considered to be adap 七 ed for feeding on detrital matter sllch as appendicularian houses， Some heterorhabdids probably inject a venom or anesthetic into preγ animals to capture them ． III the laboratory ， predatien on 丘sh eggs and larvae by copepods ， rejection of solne dino 且agellates by calanoids ， developme皿 七 al inhibition of copepod eggs by feeding on some diatoms ， and copepods ， reactions to fecal pelle 七 s were demonstra七 ed ． Pelagic copepods constitllte an assemblage of evolutionarily different groups ． Among the 100rders， calanoids supposedly 丘rst colonized the marine pelagic realm ， and ， at present ， are mQst successfully adapted Qf any ordeT to this environment by a wide var 三 ety of feeding mecha 皿 isms、 They have developed a wide var 三 ety of feed 三 ng mecha 皿 isms． On the other hand ， poecilostomatoids have secondarily become adapted to pelagic environments and are loosely associated with 且sh larvae and pelagic invertebrates ， such as salps and appendicularians 〕 f（）r feeding ． The calanoid family Heterorhabdidae consists of 2 particle ・ feedi 皿 g， 3carnivorous ， and 2 intermediate genera ． A phylogenetic analysis shQwed that the ca 皿 ivores ceUld have originated from the particle − feeders through the intermediate conditions ， and that the mouthpart ele e 且 ts of the camivores could be derived from thQse of the particle − feeders with mod ． ifica 七 iolls of も he original e｝ ements a 皿 d no addition of novel structures ． Recent studies demonstrate that some copepods such as scolecitriChids and Onc αe α can eMcientl ｝ 厂 feed o 駐 nanopla 皿 1（to且 trapPed 三 n apPendicularian houses， and ajso suggest that suspension −feeders Inay transport diatom resting spores into the sea ． bottom in the epipelagic zQne and metals in the deep−sea bottoms through their feeding behavior ， and thaも epipelagic carnivores may compete with 丘sh larvae f ' ）r cQpepod nauplii and dinQ 且agellates ． 1． は じめ に ' 1997 年 5 月 6 日 受 領 il997 年 7 月 11 ． 日受 理 広 島 大 学生 物 生 産学 部 附 属水 産 実 験所 1 〒 725 広 島県竹 原 市 港 町 5−8−1 東 京 大 学梅 洋研 究所 i 〒 164 東 京 都 中 野 区 南台 1−15・ 1