Anurida maritima
Encyclopedia
Anurida maritima is a cosmopolitan
collembolan
of the intertidal zone
. It is often found in aggregations of up to several hundred on the surface of rock-pools
.
animal, typically up to 3 mm long, and dark slaty blue in colour. Its body is roundish, expanding slightly towards the rear. The head
bears a pair of eye
s and a single pair of antennae
, the thorax
comprises three body segments, each of which bears one pair of legs
, while the abdomen
comprises six segments. The entire body is covered with white hydrophobic hairs which allow the animal to stay above the surface of the water on which it spends much of its life. Unlike other springtails, A. maritima cannot leap, since its furcula
is vestigial.
s and tidal marsh
es. In the British Isles, it is missing from the north-east of Scotland
and has not been recorded from south-east Ireland. It is also absent from the Baltic Sea
. There have been suggestions that the animals found in northern Europe may be a different species from that found in the Mediterranean Sea
.
In the warmer parts of its range, A. maritima is active throughout the year, but in cooler temperate
regions, it is only active in the summer months, overwinter
ing as eggs
.
of the upper intertidal zone, feeding on dead animals, chiefly crustacean
s (including barnacle
s) and molluscs
.
Aggregation is an important aspect of collembolan biology, and A. maritima has been shown to produce an aggregating pheromone
. Like many intertidal animals, A. maritima moves in rhythm with the tidal cycle, and has an endogenous
circatidal rhythm with a period of 12.4 hours, using visual cues to orientate themselves during their movements.
Cosmopolitan distribution
In biogeography, a taxon is said to have a cosmopolitan distribution if its range extends across all or most of the world in appropriate habitats. For instance, the killer whale has a cosmopolitan distribution, extending over most of the world's oceans. Other examples include humans, the lichen...
collembolan
Springtail
Springtails form the largest of the three lineages of modern hexapods that are no longer considered insects...
of the intertidal zone
Intertidal zone
The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...
. It is often found in aggregations of up to several hundred on the surface of rock-pools
Tide pool
Tide pools are rocky pools by oceans that are filled with seawater. Many of these pools exist as separate entities only at low tide.Tide pools are habitats of uniquely adaptable animals that have engaged the special attention of naturalists and marine biologists, as well as philosophical...
.
Description
A. maritima is a winglessApterygota
The name Apterygota is sometimes applied to a subclass of small, agile insects, distinguished from other insects by their lack of wings in the present and in their evolutionary history...
animal, typically up to 3 mm long, and dark slaty blue in colour. Its body is roundish, expanding slightly towards the rear. The head
Head
In anatomy, the head of an animal is the rostral part that usually comprises the brain, eyes, ears, nose and mouth . Some very simple animals may not have a head, but many bilaterally symmetric forms do....
bears a pair of eye
Eye
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 and a single 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....
, the thorax
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...
comprises three body segments, each of which bears one pair of legs
Arthropod leg
The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments are of Latin origin, and may be confused with terms for bones: coxa , trochanter , femur, tibia, tarsus, ischium, metatarsus, carpus, dactylus ,...
, while 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...
comprises six segments. The entire body is covered with white hydrophobic hairs which allow the animal to stay above the surface of the water on which it spends much of its life. Unlike other springtails, A. maritima cannot leap, since its furcula
Furcula (Collembola)
The furcula, or furca, is a tail-like appendage shaped like a fork, found ventrally on the fourth abdominal segment of springtails. Present in most species dwelling the upper soil layers, it is used for jumping when the animal is threatened...
is vestigial.
Distribution and ecology
A. maritima is found around the world on rocky shoreRocky shore
A rocky shore is an intertidal area of seacoasts where solid rock predominates. Rocky shores are biologically rich environments, and make the ideal natural laboratory for studying intertidal ecology and other biological processes...
s and tidal marsh
Tidal marsh
A tidal marsh is a type of marsh that is found along coasts and estuaries of which the flooding characteristics are determined by the tidal movement of the adjacent estuary, sea or ocean . According to the salinity of the flooding water, freshwater, brackish and saline tidal marshes are...
es. In the British Isles, it is missing from the north-east of Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
and has not been recorded from south-east Ireland. It is also absent from the Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...
. There have been suggestions that the animals found in northern Europe may be a different species from that found in 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 the warmer parts of its range, A. maritima is active throughout the year, but in cooler temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
regions, it is only active in the summer months, overwinter
Overwinter
To overwinter is to pass through or wait out the winter season, or to pass through that period of the year when “winter” conditions make normal activity or even survival difficult or near impossible...
ing as eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
.
Ecology
A. maritima is a significant scavengerScavenger
Scavenging is both a carnivorous and herbivorous feeding behavior in which individual scavengers search out dead animal and dead plant biomass on which to feed. The eating of carrion from the same species is referred to as cannibalism. Scavengers play an important role in the ecosystem by...
of the upper intertidal zone, feeding on dead animals, chiefly crustacean
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...
s (including barnacle
Barnacle
A barnacle is a type of arthropod belonging to infraclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile suspension feeders, and have...
s) and molluscs
Mollusca
The Mollusca , common name molluscs or mollusksSpelled mollusks in the USA, see reasons given in Rosenberg's ; for the spelling mollusc see the reasons given by , is a large phylum of invertebrate animals. There are around 85,000 recognized extant species of molluscs. Mollusca is the largest...
.
Aggregation is an important aspect of collembolan biology, and A. maritima has been shown to produce an aggregating pheromone
Pheromone
A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...
. Like many intertidal animals, A. maritima moves in rhythm with the tidal cycle, and has an endogenous
Endogenous
Endogenous substances are those that originate from within an organism, tissue, or cell. Endogenous retroviruses are caused by ancient infections of germ cells in humans, mammals and other vertebrates...
circatidal rhythm with a period of 12.4 hours, using visual cues to orientate themselves during their movements.