BIOTIC Species Information for Talitrus saltator
|Researched by||Georgina Budd||Data supplied by||MarLIN|
|Refereed by||This information is not refereed.|
|Scientific name||Talitrus saltator||Common name||A sand hopper|
|MCS Code||S241||Recent Synonyms||Talitrus locusta|
|Additional Information||An extensive review of the Talitridae was published by Bulycheva (1957) in which the concept of the family was reconsidered and a number of genera removed to newly erected families, Hyalidae and Hyalellidae. The separation provides a convenient ecological grouping with the truly terrestrial genera in the Talitridae, a family consisting of five genera (Talitrus, Orchestia, Talorchestia, Talitroides and Brevitalitrus), all of which are recorded in the British Isles. Talitrus are a small circumtropical genus comprising about 10 recognized species but Talitrus saltator is the only species that extends into the north east Atlantic area (Lincoln, 1979).|
|Taxonomy References||Reid, 1947, Howson & Picton, 1997, Lincoln, 1979, Bulycheva, 1957,|
See additional information
|Typical food types||Partly decayed seaweed and other vegetation.||Habit||Free living|
|Bioturbator||Flexibility||High (>45 degrees)|
|Height||Insufficient information||Growth Rate||1.3-5.5mm/100 days depending on life stage|
|Adult dispersal potential||100-1000m||Dependency||Independent|
|General Biology Additional Information||Growth rate
Williams (1978) reported that juvenile growth rates averaged 5.5 mm in 100 days decreasing to 1.3 mm in 100 days after sexual differentiation at around 8.0 mm.
The leaping habit of the Talitridae is confined to the family and is achieved by the sudden extension of the intucked, short posterior end of the body. In order to achieve a leap, the species has to stand on its legs in a manner not characteristic of the Amphipoda, which normally move on their side. The sudden tail-flick is undirected and it may land anywhere. Hopping is repeated until a safe place is found (Reid, 1947).
Pattern of activity
Despite the widespread occurrence of Talitrus saltator in the supralittoral zone of sandy beaches along the Atlantic coasts of Europe and the Mediterranean (Dahl, 1952), most work concerning the species has focused on its behaviour, in particular influences on the locomotor activity rhythm of the species e.g. Williams (1980, 1979, Williams, J.A., 1983).
During the day, Talitrus saltator is found buried in the substratum above the high tide line but, at night it emerges on the ebb tide to forage intertidally on the strandline algae. It must, however, return to the high supralittoral before the flood tide. Williams, J.A. (1983) found that this activity was under a precise endogenously controlled rhythm, which in constant conditions will free-run for > 100 days without variation.
Following specific light cues at dawn (a threshold light intensity of 1.5 lux, Williams, 1980), nocturnal surface foraging activity ceases and the sand hopper moves upshore in order to locate burrowing sites above the previous high tide level. This dawn upshore migration is also controlled by an endogenous circadian rhythm, probably independent of that controlling emergence and foraging (Hayward, 1994), as following peak nocturnal activity, the sand hopper quite suddenly switches to orientated movement in the direction of light/dark boundaries (horizon). A behaviour that Edwards & Naylor (1987) demonstrated experimentally.
The activity cycle of Talitrus saltator is also entirely circadian. Its nocturnal activity in the intertidal zone occupies a six to eight hour period which, peaks between 0100 and 0300 hours GMT regardless of tidal state and cycles over a period of 24.46 hours. Owing to the requirement for the activity pattern to be phased with the seasonally changing night/day ratio (nL/D) a perceptible daily shift is apparent (Hayward, 1994). Williams (1980) found that the dawn light transition, rather than dusk, was used by Talitrus saltator to synchronize its periods of activity with the nL/D cycle.
The pattern of behaviour seems to serve two purposes. Firstly, it prevents the sand hoppers' burrow zone being completely inundated during the next high tide and consequently a semi-lunar horizontal displacement of the burrow zone occurs (Williams, 1979).
Secondly, the activity is related to humidity. Moisture conservation is a major stress for crustaceans living a transition between marine and terrestrial life-styles and behavioural mechanisms used to locate and maintain humid microhabitats during the diurnal quiescent phase of their circadian activity cycle is vital.
Differences in physical morphology and behaviour are reported (Scapini et al., 1999). For instance, where tides are virtually absent in parts of the Mediterranean, the sand hopper moves landwards beyond high water to forage (Scapini et al., 1992). It navigates back to the supralittoral zone, using celestial orientation, with a circadian timing that is reinforced by visual clues (e.g. Mezzetti & Scapini, 1995; Ugolini & Scapini, 1988).
In conclusion, endogenous behaviour rhythms are especially important in mobile intertidal organisms for the maintenance of a zoned distribution on the shore and for the synchronization of whole population behaviour, vital for reproduction.
|Biology References||Williams, 1979, Dahl, 1946, Dahl, 1952, Hayward, 1994, Williams, J.A., 1983, Williams, 1983b, Williams, 1980, Edwards & Naylor, 1987, Scapini et al., 1999, Mezzetti & Scapini, 1995, Scapini et al., 1992, Ugolini & Scapini, 1988,|
|Distribution and Habitat|
|Distribution in Britain & Ireland||Locally common on all coasts of Britain and Ireland.|
|Global distribution||In the N.E. Atlantic and North Sea, along European coasts from southern Norway to the western Mediterranean.|
|Biogeographic range||Not researched||Depth range||Supralittoral|
|Migratory||Non-migratory / Resident|
|Distribution Additional Information||During the winter quiescent populations can be found burrowed above the extreme high water spring tide mark, at depths up to 50 cm (Bregazzi & Naylor, 1972; Williams, J.A.,1976). From field studies, Williams (1983b) found that the majority of adults burrowed down in to the substratum until sand with at least 2% moisture content is encountered. Recently hatched juveniles are considered to be physically incapable of burrowing in order to avoid desiccation (Williams, 1978) and are consequently found amongst freshly deposited seaweed that maintains a relatively high humidity of 85-90% over the low tide (Williamson, 1951).|
||Physiographic preferences||Open coast
Strait / sound
Enclosed coast / Embayment
||Wave exposure||Not relevant
|Tidal stream strength/Water flow||Not relevant
|Habitat Preferences Additional Information|
|Distribution References||Lincoln, 1979, Williams, 1983b, Hudson & Reynolds, 1984, Bregazzi & Naylor, 1972, Williams, J.A., 1976,|
|Reproductive Season||May to August||Reproductive Location||As adult|
|Reproductive frequency||Annual episodic||Regeneration potential||No|
|Life span||1-2 years||Age at reproductive maturity||<1 year|
|Generation time||<1 year||Fecundity||Up to 15 eggs per brood|
|Egg/propagule size||Not relevant||Fertilization type||Internal|
|Reproduction Preferences Additional Information||Sexes are separate. It is possible to distinguish between sexes in specimens with a body length between 8.0 and 8.5 mm (Williams, 1978). For a description of embryonic development in Talitrus saltator see Williams (1978, Figure 1). All eggs within a single brood are at the same stage of morphological development. For a female of 12.6 mm length the mean number of eggs per brood is 13, larger females may carry a slightly larger brood of 15.
As in all crustaceans, mating and the release of juveniles, are synchronised with the moult cycle. Adults pair during their nightly migration down the beach and mate in the sand once the female has completed her moult. In the Isle of Man, Williams (1978) first caught egg bearing females in samples during May with high reproductive activity occurring between May and late August so that by September all brood pouches were found to be empty. This breeding cycle is in contrast to those of other intertidal amphipods and isopods (Hayward, 1994) in that the breeding period is shorter and controlled by day length (Talitrus saltator breeds when the natural day length is in excess of 14 hours (Williams, 1985)) irrespective of air and sea temperature (Williams, 1978). Williams (1978) found two generations to be present over a year and females died during their second over-wintering period, before the males. Williams (1978) calculated the life span of females to be ca 18 months and 21 months for males. Juveniles become sexually differentiated within three to four months of hatching and do not contribute to a precocious, secondary breeding population in the summer, they usually reach maturity by the autumn and do not breed until the following summer. The over-wintering population consists of young adults, with an additional number of juveniles arising from the last brood of the season and a few large sexually mature adults that were the last to breed. Such adults die in February, so that the young adults and maturing juveniles that overwintered, constitute the new breeding population (Williams, 1987; Hayward, 1994).
|Reproduction References||Williams, 1978, Hayward, 1994, Williams, 1985,|