Animal classes

Crustaceans (Amphipoda)

Amphipods are small, fast moving (mostly swimming) crustaceans with laterally compressed bodies. Amphipods are characterized and differentiated from crustaceans by the absence of a carapace or shell over the front part of the body. The name "amphipoda" is derived from the Greek roots "amph" (meaning "different"), and "pod" (meaning "foot“), and refers to the superficial appearance that these animals have two distinct types of leg-like appendages - swimming and feeding appendages.

Amphipods can grow up to 60 millimetres, but they are typically less than 15 millimetres long. The body of an amphipod is divided into a head, a thorax and an abdomen. They possess large compound eyes on either side of the head. Unlike the eyes of shrimps or crabs, these eyes are not on stalks. On the head they have two pairs of antennae, with one pair usually very small, the mandibles, two pairs of maxillae and one pair of maxilliped. The thorax and abdomen are usually quite distinct and bear different kinds of legs. Thoracic legs are adapted for swimming, while modified hind legs are adapted for both rowing and leaping. Gills are present on the thoracic segments, where also the glands may be found. First four pairs of female's pereiopods form chamber in which the eggs are carried between laying and hatching.

Around 7,000 species of amphipods have so far been described. Alicella gigantea (up to 14cm) and Eurythes gryllus (up to 11 cm) are the largest species of amphipods ever observed. Amphipods are placed in four suborders: Gammaridea, Ingolfiellidea, Hyperiidea i Caprellidea. Most of the species are classified into one suborder Gammaridea (approximately 80% of all species). In Croatia there is more than 140 species been found.

Amphipods live in an enormous variety of habitats, mostly sea. They also live in freshwater environments (streams, rivers, ponds, wetlands, bractic waters). The coarse sand or moist ground also offer a suitable habitat for amphipods. Parasitic amphipods are known from surface waters (Cyamidae, Hyperiidea). Most species of whale louse (Cyamidae) are associated with a single species of whale. Around 10 000 whale louse could live on a single whale.

The stygofauna of entire continents is sometimes dominated by amphipods. Alike other stygobiotic organisims, amphipods also show various degrees of adaptation to their particular habitats, usually expressed by loss of eye pigment and loss of body pigmentation, relatively greater slenderness of the body, elongation of certain body appendages (antennae, pereiopods, uropods), reduced offspring, etc. Stygobiotic amphipods feed often on microorganisms, such as yeasts, growing on cave loam, bat manure, etc., but certain species feed on rotting plant debris as well. For some species predatory habits are made plausible.

Most of the species inhabit subterranean waters and constitute a substantial part of Europe’s groundwater biodiversity. The genus is distributed across most of Europe. In Croatia live large number of narrowly endemic Niphargus group species such as Niphargus croaticus, N. aquilex, N. buturovici, N. echion, N. numerus, N. pectencoronatae, etc.

Order Gammaridae consists from many genera which encompass many endemic species from Croatia alike Accubogammarus algor jalzici, Bogidiellla glacialis, Echinogammarus acarinatus, Fontogammarus dalmatinus and Melita valesi.

Contact:

P. Kutleša -

Literature:

Botosaneanu L. (1986), Stygofauna mundi: a faunistic, distributional, and ecological synthesis of the world fauna inhabiting subterranean waters (including the marine interstitial), E.J. Brill, Leiden, the Netherlands.

Matoničkin I., Habdija I. & Primc-Habdija B. (1999): Beskralješnjaci – Biologija viših avertebrata, Školska knjiga, Zagreb

http://niphargus.info/ (Contents created and maintained by researchers from Dept. of biology, Biotechnical faculty,University of Ljubljana, Cene Fišer, Peter Trontelj and Boris Sket.)