Isopods

Classification:

Kingdom: Animalia

Clade: Euathropoda

Sub-Phylum: Crustacea

Class: Malacostraca

Order: Isopoda

Armadillidium Vulgare rolled up into a ball.

Characteristics of Isopods

Isopods are a broad order of animals that range from marine parasites to soil dwelling mesofauna and macrofauna. Typical characteristics of Isopods is that they have an elongated body that is relatively flat with segmented plates across their back. They have three main regions to their body similar to insects, the head, thorax and abdomen. The heads (sometimes called cephalons) of Isopods have compound eyes, two pairs of antennae, and four sets of jaws. Typically the upper pair of antennae on isopods are chemosensory structures while the lower pair of antennae are usually used as feelers. Isopods all have sessile eyes which means they are directly on the body and are not connected via a stem or stalk. Their midsection is called their thorax (sometimes called pereon) and is the central part of their body and consists of the seven segments after the first which is where the head is fused to the thorax. Typically, terrestrial isopods (Woodlice) have a pair of legs attached to each segment of the thorax that have flexible joints that are used for moving the legs. The tail end section of isopods is called the abdomen (or pleon) and it is where the tail segments of their chitinous plates are. The abdomen usually consists of six plates, five of which are simply used as defensive plates that can be used to help curl into a ball, and another pointed plate which functions as a tail to help maneuver in water. Underneath these plates are flattened gills that are used to aid the isopod in respiration and other body functions.

Terrestrial Isopods

Isopods that have fully transitioned to being terrestrial Organisms are in the suborder Oniscidea which consists of around 5,000 species. Colloquial names for terrestrial isopods are Pillbugs, Sowbugs, and Woodlice. They are typically found in the O-Horizon in soil or on top/under fallen trees on the forest floor. Isopods are prey to many predators ranging from foxes to beetles and even some species of owls, thus they are an important part of the ecosystem as both detritivores that aid in decomposition vegetation and as prey for those higher up on the food chain.

Oniscus Asellus

Phytoremediation

Terrestrial Isopods are either Detritivores or microphyophages. Isopods have been known to remove heavy metals from the soil, most notably Copper, Cadmium, Lead, and Zinc. They have been used in studies to discover the degree of metal contamination within soil. It has been noted that low concentrations of copper in isopods has been shown to stimulate growth rate in juveniles while high concentrations of copper spurt growth in isopods. Certain species of isopods have been known to distinguish between plant leaves with high cadmium sulphate levels and avoid eating them.

Isopods Diet

Isopods can fall into one or more of the following niches: detritivores, browsers, carnivores, parasites, and filter feeders.

Aquatic isopods always fall in the filter feeder or parasite niche. This being said, the filter feeders eat dead plant materials and algae off off stones and logs that reside on the bottom of bodies of waters. Parasitic isopods are external blood feeders that reside in a fishes buccal cavities and shrimp and crabs gill cavities.

Terrestrial isopods are generally herbivores and fall under the rest of the niches. They eat on a range of materials that include moss, bark, algae, fungi, and decaying material. The said fungi on trees hold amounts of nitrogen that allow isopods to include nitrogen in their diet.

References

1. Tree of Life Isopoda. (n.d.). . http://tolweb.org/Isopoda/6320/1997.08.06.

2. Ddblade. (n.d.). . https://www3.northern.edu/natsource/INVERT1/Pillbu1.htm.

3. Magrini, M. J., A. V. L. Freitas, and M. Uehara-Prado. 2011. The effects of four types of anthropogenic disturbances on composition and abundance of terrestrial isopods (Isopoda: Oniscidea). Zoologia (Curitiba) 28:63–71.

4. Cortet, J. C. A. C. B., A. G.-D. Vauflery, N. Poinsot-Balaguer, L. Gomot, C. Texier, and D. Cluzeau. 1999. The use of invertebrate soil fauna in monitoring pollutant effects. European Journal of Soil Biology 35:115–134.

5. Brigić, A., I. Antonović, A. Alegro, V. Šegota, and J. Bujan. 2017. Terrestrial isopods (Isopoda: Oniscidea) as unexpected inhabitants of extreme habitats. European Journal of Soil Biology 82:66–71.

6. Hattenschwiler, S., S. Buhler, and C. Korner. 1999. Quality, Decomposition and Isopod Consumption of Tree Litter Produced under Elevated CO 2. Oikos 85:271.