摘要:

Conditioning experiments were conducted to test the ability of western Atlantic spiny lobsters(Panulirus argus)to orient using geomagnetic cues. Lobsters were trained and tested in a rotatable circular orientation apparatus in which they could enter tunnels aligned with one of six compass bearings. In initial experiments animals were positively reinforced for entering the tunnel at magnetic north and negatively reinforced for entering all other tunnels. While deprived of all known or suspected guideposts other than the geomagnetic field, conditioned lobsters entered tunnels aligned with the north‐south magnetic axis significantly more often than other tunnels. However, the animals did not demonstrate the ability to discriminate north from south under the experimental conditions.

ISSN:0091-181X    

DOI:10.1080/10236248509378629

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Crabs of the genusTrapezia, obligate symbionts of reef corals, typically occur as heterosexual pairs, with a single pair of a given species per coral colony. Pair formation, and the effects of size on pairing, were studied inT. intermediaandT. digitalisin Hawaii, inT. tigrina, T. rufopunctata, and T. dentataat Enewetak Atoll, Marshall Islands, and inT. corallinaat Panama. When a male and female of the same species were placed on separate corals, either the male or the female usually moved to the colony inhabited by the other crab, resulting in the formation of a pair. Both males and females paired with the larger of two prospective mates significantly more often than expected on the basis of random pairing; the “preference” for large mates did not vary with the relative sizes of the crabs. The distribution of injuries which occurred in the experiments indicated that there was aggressive competition for mates between members of the same sex. While the experimental results can be explained by intra‐sexual competition for mates, the hypothesis that crabs exercise choice for large mates cannot be ruled out, and possible adaptive advantages of mate choice are discussed.

ISSN:0091-181X    

DOI:10.1080/10236248509378630

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Food passed by the chelate pereiopods to the mouthparts ofPenaeus merguiensisde Man is propelled dorsally to the mouth through a pre‐oral cavity made up of the setal fringes of the first two pairs of maxillipeds and the two pairs of maxillae. The setal fringes interdigitate and move with a ratchet action. Food is sheared off and crushed by the mandibles, pushed into the oesophagus by the setae on the labrum and prevented from escaping from the mouth by the paragnaths and labrum. In addition to setae, the endopods of the second maxillipeds and the paragnaths have glands the pores of which open on to their surfaces. Non food items are expelled by downward directed movements of the appendages forming the pre‐oral cavity.

ISSN:0091-181X    

DOI:10.1080/10236248509378631

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Biphasic potentials are recorded in the column and tentacles ofPachycerianthus fimbriatusfollowing stimulation by a single electrical shock of a through conducting system anywhere on the column. Magnesium is shown to first increase the conduction delay and number of potentials in the response and then eliminate it. A second electrical response, trains of spikes, stimulated by application ofAnemia“juice” is present in the tentacles.

ISSN:0091-181X    

DOI:10.1080/10236248509378632

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A beaugregory damselfish(Eupomacentrus leucostictus)population in Jamaica, W.I., was censured and revealed continuous changes in numbers of individuals for all size classes. The smallest size class, juveniles, was most abundant on the loose sand substratum while adults were common only in areas with numerous pieces of small rubble. The change in habitat from juvenile to adult is attributed to both selected mortality and active movement of the juveniles.

ISSN:0091-181X    

DOI:10.1080/10236248509378633

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0091-181X    

DOI:10.1080/10236248509378628

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor