摘要:

Samples of adult sandsmelt populations (Atherina boyeriRisso 1810) from sites along the Italian coasts and from an inland lake were compared by discriminant function analysis of morphometric traits. Differences were due to age‐cohorts rather than to localities of provenience.

ISSN:0373-4137    

DOI:10.1080/11250008809386608

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The eyes ofProtzia constansconsist of anterior and posterior biconvex lenses that are lamellate and have a thin cuticular layer with pore canals on the dorsal surface. There are four retinula cells beneath each lens and no vitreous cone or preretinal membrane is associated with either lens. The rhabdomeres are in direct contact with the lenses and are fused into a single rhabdom. The visual pigments are situated under each rhabdomere and along the sides. Secondary pigments are concentrated between the cuticule of the body and the retinula cells, and between the retinular regions under each lens. These pigments are a type of lipid(s) that provide a barrier to extraneous light. The cuticle of the eye capsule forms a long extension that reaches into the body cavity and a muscle is attached to the cuticular estension. This muscle is probably capable of changing the position of the lateral eye in respect to the light

ISSN:0373-4137    

DOI:10.1080/11250008809386609

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

TheHolothuria poliiamebocytes produce two molecules of about 80 KDa molecular weight, serologically identical but with different chemico‐physical characteristics. A calcium‐dependent, heat‐sensible hemolysin (hemolysin 1) appears to be released under natural conditions, while a calcium‐independent, heat‐stable hemolysin (hemolysin 2) is produced under immunological stimulation. Both are able to interact with foreign cell surfaces probably through membrane sphingomyeline, producing serious damage leading to lysis. The molecules also act as opsonic elements. In the present paper a possible phylogenetic interpretation of the origin of these hemoly‐sins is discussed on the basis of similar effects observed in invertebrates and in relation to vertebrate complement and perforin.

ISSN:0373-4137    

DOI:10.1080/11250008809386610

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The maturation of the lateral line system inAnguilla anguilla(L.) is described. The various stages of eel (glass‐eel, yellow eel, silver eel), which are characterized by different degrees of swimming activity were compared, and changes were observed in the lateral line system during the transition from yellow eel to silver eel. The most evident changes occur in the pattern of the head canals and in the continuation of the lateral body canals as far as the caudal fin. These changes appear to be related to the greater swimming activity displayed by the silver eel.

ISSN:0373-4137    

DOI:10.1080/11250008809386611

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Albino mouse pups with no experience of solid food, were allowed access to standard food pellets at 16, 18 or 20 days of age. Ten litters were used for each group. For the test, each litter was split into two groups of four pups, two males and two females. Groups were observed for 30 minutes with or without the mother. The experimental apparatus consisted of eight food pellets alternating with eight corks, in fixed and numbered positions, placed in surroundings unknown to both the pups and the mothers. The pups only bit the food, whilst the mothers bit also the inedible material. The pups preferred to feed in isolation and in particular locations within the area. Age increased the proportion of feeding pups, decreased latency and extended feeding activity in space. The sex of pups did not affect the experiment. The presence of the mother increased feeding activity in 16‐day‐old offspring but reduced it in 20‐day‐old counterparts.

ISSN:0373-4137    

DOI:10.1080/11250008809386612

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The daily feeding rhythms of five species of mullet fry(Liza ramada, Liza aurata, Liza saliens, Mugil cephalusandChelon labrosus)were investigated by analyzing their stomach fullness during 24‐hour cycles. Light is the major abiotic factor influencing the feeding rhythm of the fry. Feeding activity occurs prevalently during day‐time with a clear unimodal feeding cycle. OnlyL. saliensfry show a bimodal feeding cycle, with a secondary peak around sunset. Differences in the feeding activity rhythm are probably due to larger individuals which, unlike the smaller individuals, show preferential twilight feeding. Tides and temperature play a secondary role and their influence is probably masked by the light effect.

ISSN:0373-4137    

DOI:10.1080/11250008809386613

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The diet of fry ofMugil cepbalus, Uza aurata, Uza ramada, Liza saliens, Chelon labrosus, caught over 24‐hour cycles, during the peak migrating period of each species was studied. Stomach contents were studied by means of qualitative and quantitative methods. The five species feed mainly during the morning hours. Their diet largely consists of small freshwater planktonic forms, but benthonic organisms, e.g. insect larvae, although few in number, represent a considerable fraction of the ingested food. Similarity in the diet of simultaneously caught species was also tested.Chelm labrosusandUza auratahave significantly different diets. Due to its larger size, the fry ofL. aurataare predominantly bottom feeders, and they ingestes the food throughout the day.L. saliensandM. cepbalusingest the same food items, and to reduce competition,M. cephalusalso feeds at dusk. Moreover, the larger specimens ofL. saliensingest greater quantities of larger zoobenthonic organisms.

ISSN:0373-4137    

DOI:10.1080/11250008809386614

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

An epizoic colonial peritrich,Zoothamnium intermediumPrecht, collected from the lagoon Valle Fossa di Porto (Ferrara, Italy), is described on the basis of light and scanning electron microscope observations. It was found on the copepodsAcartia clausi, A. latist‐tosa, Calanipeda aquaedulcisand zoeae of the shrimpHippolyte longiros‐tris.InA. clausi, which was the most abundant species of the Zooplankton community, Z.intermediumwas distributed over the whole body surface of 99.3% of specimens. Numerous rod‐shaped bacteria were found in association with the attachment sites of Z.intermedium.

ISSN:0373-4137    

DOI:10.1080/11250008809386615

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The association between the peritrich ciliateSçypbidiasp. and a population ofNerilla antennatafrom the Livorno coast is reported for the first time. Some details of the epibiont's morphology obtained by SEM are given. Data on the frequency of this epibiosis show a marked difference between adult and juvenileNerillae, being much higher in adult worms.

ISSN:0373-4137    

DOI:10.1080/11250008809386616

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A study has been conducted on the Bryozoa from the Mediterranean and Red Sea coasts of Israel. Most specimens were from the collections of the Zoological Museum of Tel Aviv University. The paper includes descriptions of two new species,Chaperia infundibu‐lata, n. sp. andCelleporaria trispiculata, n. sp., and of the new sub‐genusRetiscrupoccllaria, subgn. nov, with the rehabilitation of the speciesCanda filiferaLamarck, 1816.

ISSN:0373-4137    

DOI:10.1080/11250008809386617

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor