''Talitrus saltator'', a species of sand hopper, is a common amphipod

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

of sandy coasts around Europe. The animal's typical "hopping" movement gives it its

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contra ...

, and is produced by a

flexion Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

of the

abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the tors ...

. In order to do this, it must stand on its legs (amphipods usually rest on their sides) and suddenly extend its abdomen from under its body. It can thus leap several inches into the air, although without any control over its direction. A great deal of

scientific research The scientific method is an empirical method for acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries; see the article history of scientific ...

has been carried out on the animal, to determine the

environmental cues A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale fr ...

which it uses to control its

behavior Behavior (American English) or behaviour ( British English) is the range of actions and mannerisms made by individuals, organisms, systems or artificial entities in some environment. These systems can include other systems or organisms as w ...

Description

''Talitrus saltator'' reaches lengths between and , with males being slightly larger than females. The body is grayish-brown or grayish-green in colour, with a single pair of black eyes. It has a distinct pair of antennae, with one antenna as more robust than the other.

Distribution

''Talitrus saltator'' is found around the coasts of the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...

and north-east

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth#Surface, Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Afr ...

from southern

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

to the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ...

. In most of its range, its daily cycle is strongly linked to the

tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables can ...

s, with daily migrations of up to , but where there are no significant tides (as in parts of the Mediterranean), visual cues are used instead.

Life cycle

Mating occurs in ''T. saltator'' once the

photoperiod Photoperiodism is the physiological reaction of organisms to the length of night or a dark period. It occurs in plants and animals. Plant photoperiodism can also be defined as the developmental responses of plants to the relative lengths of light a ...

exceeds 14 hours; this is in contrast to other shoreline animals such as

isopods Isopoda is an order of crustaceans that includes woodlice and their relatives. Isopods live in the sea, in fresh water, or on land. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, an ...

which use

air temperature Atmospheric temperature is a measure of temperature at different levels of the Earth's atmosphere. It is governed by many factors, including incoming solar radiation, humidity and altitude. When discussing surface air temperature, the annual at ...

or sea temperature to control breeding times. Mating occurs during the animal's nightly migration down the beach, after the female has moulted. Broods of 13–15 eggs are carried by the females. When they first hatch, juveniles are sensitive to

desiccation Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. ...

but are unable to burrow, and so they live in washed up seaweed with a

humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity dep ...

of 85%–90%. Although the juveniles become sexually differentiated within a few months, they do not contribute to the second reproductive wave later in the year, but first reproduce the following year. Females die before the males, in their second winter (males live for 21 months, compared to 18 months for females). During the winter, adults burrow into the sand until they reach a moisture content of 2%; this may require them to dig up to deep.

Ecology

''Talitrus saltator'' spends the day buried at depths of above the strandline, but emerges at night on the falling

to feed. They are capable of navigating where the sea is using multiple indicators; including the angle of the sun, moon, or even by detecting the blue wavelengths of light from the sea and the red-brown colors of land. Their diet is composed chiefly of the rotting

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), ''Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ke ...

which accumulates on the strandline. ''T. saltator'' is an important food source for shore birds.

References

External links