Isopods
Classification:
Kingdom: Animalia
Clade: Euarthropoda
Sub-Phylum: Crustacea
Class: Malacostraca
Order: Isopoda
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 used as feelers. All Isopods 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 used for moving the legs. The tail end section of isopods is called the abdomen (or pleon) and is where the tail segments of their chitinous plates are located. The abdomen usually consists of six plates; five of which are simply used as defensive plates that can 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, potato bugs, and woodlice. They are typically found in the O-Horizon of soil and on top or under fallen trees on the forest floor. Isopods predators range from beetles to foxes and even some species of owls. Due to the isopods' nutrient high diet, they are a great addition to many preys diet as well. With this reasoning, they are an important part of the ecosystem as both detritivores that aid in decomposition of vegetation and as a food source for other species.
Phytoremediation
Terrestrial Isopods can be Detritivores. 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 have been shown to stimulate the 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 feeding niches: detritivores, browsers, carnivores, parasites, and filter feeders.
Aquatic isopods always fall in the filter feeder or parasite niche. The filter feeders will also 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 can fall under all categories of feeding niches described. They eat a range of materials that include moss, bark, algae, fungi, and decaying material. The fungi on some trees provides amounts of nitrogen that isopods need 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.