Talitrus saltator
Encyclopedia
Talitrus saltator, a species of sand hopper, is a common amphipod crustacean
of sandy coasts around Europe
. The animal's typical "hopping" movement gives the animal its common name
, and is produced by a flexion
of the abdomen
. In order to do this, it must stand on its legs (amphipods usually rest on their sides) and suddenly extend its abdomen out 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 has been carried out on the animal, to determine the environmental cues it uses to control its behaviour.
s. It has a distinct pair of antennae
, with one antenna more robust than the other.
and north-east Atlantic Ocean
from southern Norway
to the Mediterranean Sea
. In most of its range, its daily cycle is strongly linked to the tide
s, with daily migrations of up to 100 m (328 ft), but where there are no significant tides (as in parts of the Mediterranean), visual cues are used instead.
. Brood
s of 13–15 eggs are carried by the females. When they first hatch, juvelines are sensitive to desiccation
but are unable to burrow, and so they live in washed up seaweed with a humidity
of 85%–90%. Although the juvelines 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 50 cm (20 in) deep.
, but emerges at night on the falling tide
to feed. Their diet is composed chiefly of the rotting
seaweed
which accumulates on the strandline. T. saltator is an important food source for shore birds
.
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
of sandy coasts around Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
. The animal's typical "hopping" movement gives the animal its common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
, and is produced by a flexion
Flexion
In anatomy, flexion is a position that is made possible by the joint angle decreasing. The skeletal and muscular systems work together to move the joint into a "flexed" position. For example the elbow is flexed when the hand is brought closer to the shoulder...
of the abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
. In order to do this, it must stand on its legs (amphipods usually rest on their sides) and suddenly extend its abdomen out 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 has been carried out on the animal, to determine the environmental cues it uses to control its behaviour.
Description
Talitrus saltator reaches lengths between 8.2 mm (0.322834645669291 in) and 16.5 mm (0.649606299212598 in), with males being slightly larger than females. The body is greyish-brown or greyish-green in colour, with a single pair of black eyeEye
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...
s. It has a distinct pair of antennae
Antenna (biology)
Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....
, with one antenna more robust than the other.
Distribution
Talitrus saltator is found around the coasts of the North SeaNorth Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
and north-east Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
from southern Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
to the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
. In most of its range, its daily cycle is strongly linked to the tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
s, with daily migrations of up to 100 m (328 ft), 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 exceeds 14 hours; this is in contrast to other shoreline animals such as isopods which use air temperature or sea temperature to control breeding times. Mating occurs during the animal's nightly migration down the beach, after the female has moultedEcdysis
Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...
. Brood
Offspring
In biology, offspring is the product of reproduction, of a new organism produced by one or more parents.Collective offspring may be known as a brood or progeny in a more general way...
s of 13–15 eggs are carried by the females. When they first hatch, juvelines are sensitive to desiccation
Desiccation
Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic substance that induces or sustains such a state in its local vicinity in a moderately sealed container.-Science:...
but are unable to burrow, and so they live in washed up seaweed with a humidity
Humidity
Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...
of 85%–90%. Although the juvelines become sexually differentiated
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
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 50 cm (20 in) deep.
Ecology
Talitrus saltator spends the day buried at depths of 10–30 cm (3.9–11.8 in) above the strandlineStrandline
The strandline, or high water mark, is the area at the top of a beach where debris is deposited. Where there are tides, this line is formed by the highest position of the tide, and moves up and down the beach on a fortnightly cycle...
, but emerges at night on the falling tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
to feed. Their diet is composed chiefly of the rotting
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
seaweed
Seaweed
Seaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...
which accumulates on the strandline. T. saltator is an important food source for shore birds
Wader
Waders, called shorebirds in North America , are members of the order Charadriiformes, excluding the more marine web-footed seabird groups. The latter are the skuas , gulls , terns , skimmers , and auks...
.