摘要:

Four facets of the symbiosis between the shrimpAthanas indicus(Coutière 1903) and the sea urchinEchinometra mathaei(de Blainville 1825) in the Red Sea are analyzed, i.e. (1) the constancy of the association, (2) the presence of the different postlarval stages on the host, (3) the presence of breeding adults on the host, and (4) the advantages of such a partnership. (1) Urchin-shrimp association frequently occurs in the Elat reef lagoon (about 20% ofE. mathaeiwere occupied by one shrimp, seldom two), and appears to be strictly species-specific. The behavioural mechanism underlying this specificity was of little effect when isolated specimens were looking for a shelter (shrimps reacted visually towards any dark, round solid object of unspecific outline and not necessarily a spiny one). However, once the shrimp was on its host, a number of stimuli increased selectivity: chemical (the odour ofE. mathaei), mechanical information (shrimps were repelled byDiadema setosumLeske 1778 spine movements), and the degree of comfort provided [they soon left the short-spinedTripneustes gratilla(L. 1758)]. The ecological setting also meant that any errors were highly improbable (T. gratillaoccupies the type of habitat — i.e. the open lagoon bottom — whereA. indicusnever ventures). In the laboratory, the shrimps frequently shifted from one host to another, probably because they were actively searching for their conspecifics, possibly as mates. (2) Both sexes spent their whole postlarval life in association with the host. Juveniles were rare, possibly due to the faster growth rate in smaller sized classes. (3) Ovigerous females also lived among urchin spines. The reproductive output ofA. indicusseemed to be maximized by continuous spawning in the females (at least during the breeding season) as well as the partially protandrous hermaphroditism preliminarily studied in this species. (4) Urchin spines provide shelter from predators, but experiments on host deprivation show that shrimps are also food-dependant on their hosts, sweeping up the crumbs from their meals. This broom-like activity (which falls between cleaning behaviour and food competition) raises fascinating questions as to how the evolutionary path of symbiotic relationships in the Caridea has branched off towards opposite, but just as effective, life-styles.

ISSN:0394-6975    

DOI:10.1080/03946975.1991.10539481

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The gobiine fishCaecogobius cryptophthalmusn. gen. n. sp., from a cave system on Samar Island, is described and its affinities with other gobiine genera discussed. The new species shows a high degree of adaptation to the hypogean habitat and is both the first blind hypogean fish known for the Philippine Archipelago and the only known blind cave gobiine. The variability of some morphological features related to the process of regressive evolution is described, and one of its possible causes is briefly explored.

ISSN:0394-6975    

DOI:10.1080/03946975.1991.10539482

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A new genus and species,Ericabatrachus baleensis, is described from forested localities in the Bale Mountains of Ethiopia. The new taxon seems most closely allied toPetropedetesReichenow 1874, from West Africa, and toArthroleptidesNieden 1910, which is found in Kenya and Tanzania. It resembles these genera in being associated with fast-flowing forest streams and there is circumstantial evidence of a terrestrial life cycle, perhaps similar to that observed in some species ofPetropedetes.Morphological features which are considered to justify the recognition of a new genus include the small size and distinctive habitus of the animal, significantly reduced first finger and subarticular tubercles, and a striking ventral colour pattern.

ISSN:0394-6975    

DOI:10.1080/03946975.1991.10539483

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0394-6975    

DOI:10.1080/03946975.1991.10539484

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0394-6975    

DOI:10.1080/03946975.1991.10539470

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor