So tired, can’t write anymore, too many newts…and wedding dresses and in my dreams newts wearing wedding dresses (I blame too much mescal myself). Fatigue aside, last week we met the Russian Desman, an adorable mole living on the bank of a river. This week we have a sought of roly-poly request from @queen_marceline. Hope you guys enjoy.
Issue #169 - Common Pill Bug
Kingdom – Animalia
Phylum – Arthropoda
Class – Malacostraca
Order – Isopoda
Family – Armadilliidae
Genus – Armadillidium
Species – vulgare
Related Species - The Common Pill Bug is one the many members of the Family Armadilliidae, known colloquially as Pill Woodlice or Pill Bugs
Range - Common Pill Bugs are native to Europe, with a range that stretches from the Mediterranean Basin up to Southern Scandinavia, the UK and Ireland. This species was also accidentally introduced to California where it has managed to become fairly common.
Roll up, Roll up.
The Common Pillbug is a small (around 2mm in length) terrestrial isopod with a slate grey carapace, often marked with white or brown calcium deposits, split into nine shield like plates, with each one, with the exception of the tail plate and the head, supporting a single pair of legs. Pillbugs can be distinguished from other woodlice by their relatively rotund bodies, and can be distinguished from the similar pill millipedes by counting the body plates, with the latter group possessing twelve to fifteen segments. While pillbugs, and by extentison all other woodlice, are terrestrial, they need to stay in moist places to reduce the amount of water they lose from surface evaporation. Water is important in aiding the pillbug’s respiration through an organ similar to a gill known as an air tree, and that requires oxygenated air to diffuse through water to reach it (2).
Common Pillbugs are herbivores, feeding predominantly on decaying vegetation and fungi, but also occasionally grazing on lichens and fruit such as strawberries. To defend itself the Common Pillbug coils into a ball (this behaviour earned the species the alternate colloquial name of ‘Roly Poly Bug’, with the flexible armour plating on the outside used to deter predatory attacks, and also to reduce the loss of water when caught in particularly dry weather. Despite these defences, pill bugs often fall prey to the Woodlouse Spider (Dysdera crocata), whose large fangs are adapted to punch through woodlouse armour to inject a fast acting paralytic venom into its prey’s bloodstream.
Common Pill Bugs mate in the spring, with the male targeting recently moulted females to transfer a packet of sperm to the female’s gonopores. While some species of woodlouse are monogomus, the male will leave after mating to find more females that will be receptive to his advances (3). The female after her eggs have been fertilised are kept in a pouch on the underside of her body called the marsupium. Upon hatching the larvae remain close to their mother’s marsupium, at least for the first three to four moults, before finally becoming fully independent and leaving to fend for themselves.
Five Defensively Curled Creatures
The first creatures that come to mind when people think about defensive coiling in animals are the armadillos. Ironically of the 21 extant species of armadillo, only two; the Southern three-banded armadillo (Tolypeutes matacus) and Brazilian three-banded armadillo (T. tricinctus), engage in such behaviour. Other species depend on their armour plating or fleeing into a burrow or similarly impassable barrier to defend themselves from predators,
Pangolins are also known for coiling up into armoured defensive balls, as well as being the only mammals to possess scales. This behaviour is the source of their name, with Pangolin being a variant of the Malay word ‘penggulin’ which translates to ‘something that rolls up’ (4).
The Armadillo Girdled Lizard (Ouroborus cataphractus) is another species that utilises defensive coiling as a defence, something that led to the naming of this species. When threatened the lizard grasps its tail in its mouth and forms a wheel like structure with the spines and plates of its back facing its attacker.
Not every animal that coils into a defensive position is armoured. The caterpillar of the Mother of Pearl Moth (Patania ruralis), when threatened by a predator, anchors its tail to the ground and recoils rapidly to form a wheel with its body, kick starting the rolling behaviour (5). By forming an ad-hoc wheel, the caterpillar can move up to 40 times faster than it could by simply walking.
Like the caterpillar, the Vampire Squid (Vampyrotheuthis infernalis) is another relatively unarmoured animal that practices defensive coiling when attacked. By inverting its arms and revealing an array of menacing (but soft) spikes that line its tentacles, the squid looks far bigger than it actually is. In addition to changing the animal’s size, the inverted arms also mask the animal’s photophores, allowing the Vampire Squid to quickly fade into the background.
2 - https://www.pugetsound.edu/academics/academic-resources/slater-museum/exhibits/terrestrial-panel/common-woodlouse/
3 - http://animaldiversity.org/accounts/Armadillidium_vulgare/#reproduction
4 - Judy Pearsall, ed. (2002). Concise Oxford English Dictionary (10th ed.). Oxford University Press. p. 103
5 - http://iopscience.iop.org/article/10.1088/1748-3182/6/2/026007/meta;jsessionid=B7FB1A9DF4ED3736592FBF584AFD6E2E.c5.iopscience.cld.iop.org
1 - https://farm2.staticflickr.com/1047/1096722226_8e2b4a6683.jpg
2 - https://s-media-cache-ak0.pinimg.com/originals/21/4e/68/214e68ca37ff748fcb62f01aa56c1056.jpg
3 - http://www.craftynitti.com/wp-content/uploads/2013/04/armadillo-lizard-with-spiny-tail.jpg
4 - https://s-media-cache-ak0.pinimg.com/564x/c8/e5/59/c8e55905a50100350592d6db014c5cd7.jpg
And now, with my work done I’m going to curl up in a ball until next week. Once that arrives I’ll be ready to take a meat eating bull by the horns and throw it into next issue, but until then make sure to critic, comment and suggest future issues as well as making sure you check past issues in Impurest’s Bestiary
Want more IGTA? For another armoured invertebrate, click here to see the incredibly tough Lined Chiton. Or for another isopod, albeit one a lot less friendly, click here to see the terrible Tongue Eating Louse