Invertebrates Glossary of Terms

Terminology, glossary, lexicon, mini encyclopedia of specific terms related to invertebrates (isopods, millipedes, roaches). This is for specific terms that invertebrate hobbyists (isopod / millipede / roach keepers) usually come across. Thus generic terms such as abdomen and the like are not included here.

Currently under construction (in the sense that new terms are gradually added).

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Invertebrates glossary – Letter A, a

Ameglio’s Pill Woodlouse	Common name for the isopod: Armadillidium ameglioi and its varieties/color morphs: Armadillidium ameglioi ‘Orange’ etc.
antenna	A feeler organ on the head of various invertebrates. Plural: antennae.
antennula	Secondary smaller antenna in some arthropods and crustaceans. Plural antennulae.
arthrobranchia	Branchia (gill) attached to the joint area between the body and the first podomere of the leg. Plural arthrobranchiae.
Armadillidium	Genus of isopods in the family Armadillidae, that do conglobate (able to roll into a ball when scared). Currently (May 2023) consisting of 225 accepted species.
Arcangeli’s Pill Woodlouse	Common name for the isopod: Armadillidium arcangelii.
Armadillo	Genus of isopods in the family Armadillidae, that do conglobate (able to roll into a ball when scared). Currently (May 2023) consisting of 23 accepted species. Known species in our hobby include: Armadillo officinalis, Armadillo tuberculatus.
Arthropod	Arthropods from Ancient Greek ἄρθρον (arthron) ‘joint’, and πούς (pous) ‘foot’ (gen. ποδός)) are invertebrate animals in the phylum Arthropoda. They possess an exoskeleton with a cuticle made of chitin, often mineralised with calcium carbonate, a segmented body, and paired jointed appendages.
autotomy	The voluntary shedding of a limb by snapping it off the base. Watch a crab amputating it’s own arm.

Bay-colored Pill Woodlouse	Common name for the isopod: Armadillidium badium.
Beautiful Pill Woodlouse	Common name for the isopod: Armadillidium pulchellum.
Beier’s Pill Woodlouse	Common name for the isopod: Armadillidium beieri.
bioluminescence	The emission of light by a living organism (such as a firefly). Various millipedes (such as Benoitolus siamensis and others, and also some roaches (Lucihormetica verrucosa) can also emit light.
Blaberidae	Blaberidae is a family of giant cockroaches, also called blaberids, and the second-largest cockroach family by number of species. Species we see in the roach hobby include: Blaberus craniifer, Blaberus discoidalis, Blaberus giganteus, Blaptica dubia, Corydidarum magnifica, Corydidarum pygmaea, Elliptorhina chopardi, Elliptorhina davidi, Elliptorhina javanica, Elliptorhina laevigata, Eublaberus posticus, Eublaberus sp. Ivory, Gromphadorhina oblongonota, Gromphadorhina portentosa, Gyna caffrorum, Gyna capucina, Gyna centurio, Gyna lurida, Lucihormetica subcincta, Lucihormetica verrucosa, Macropanesthia rhinoceros, Nauphoeta cinerea,* Panchlora nivea, Princisia vanwaerebeki*.
brood	The young of those invertebrates that give birth to live offspring, instead of eggs waiting to hatch. Isopods and millipedes have broods of babies, whilst roaches are producing an egg case (ootheca), containing living babies. Snails are laying eggs.

Calabrian Nosy Pill Woodlouse	Common name for the isopod: Armadillidium calabricum.
CB	CB (Captive Bred). Invertebrates that were bred in captivity.
CBB	CBB (Captive Bred and Born). Both the parents and their offspring were born in captivity.
Cephalon	In isopods, the cephalon bears the eyes, mouth, antennulae, antennae, and four pairs of mouthparts (mandibles, maxillulae, maxillae, and maxillipeds).
CH	CH (Captive Hatched). Usually refers to eggs that were taken from the wild, or from animals from wild origin and hatched in captivity.
Clown Isopod	General common name for the isopod Armadillidium klugii. Localities get in front of the common name the locality name, for example: Dubrovnik Clown Isopod.
Common Hairy Pill Woodlouse	Common name for the isopod: Trichodillidium pubescens. Another local common name is Fluffy Corfu Woodlouse.
Common Pill Woodlouse	Common name for the isopod: Armadillidium vulgare and its varieties / color morphs: A. vulgare ‘Gold’, A. vulgare ‘Magic Potion’, A. vulgare ‘Orange Vigor’ etc.
conglobation	The ability of many isopods to roll into a ball when scared. Isopod species in the genera Armadillo, Armadillidium, Cubaris and other, are able to conglobate.
Corydiidae	Corydiidae, previously known as Polyphagidae, is a family of the order Blattodea (cockroaches). Many are known as sand cockroaches. The family is divided into five subfamilies, comprising 40 genera. Some of them are: Arenivaga, Eremoblatta, Eucorydia, Hemelytroblatta, Polyphaga, Therea.
Crustacean	Crustaceans belong to the subphylum Crustacea, and form a large, diverse group of arthropods including decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods (such as insects) emerged deep in the Crustacean group, with the completed group referred to as Pancrustacea. Some crustaceans (Remipedia, Cephalocarida, Branchiopoda) are more closely related to insects and the other hexapods than they are to certain other crustaceans.
Cubaris	Genus of tropical isopods in the family Armadillidae that do conglobate (able to roll into a ball when scared). Currently (May 2023) consisting of 61 accepted species, and perhaps the double number of that are Cubaris morphs. Many of the Cubaris isopod species are native to SE Asia.

Ecdysozoa	Ecdysozoa is a group of protostome animals, including Arthropoda (insects, chelicerata, crustaceans, and myriapods), Nematoda, and several smaller phyla.
Ectobiidae	Ectobiidae (formerly Blattellidae) is a family of the order Blattodea (cockroaches). This family contains many of the smaller common household pest cockroaches, among others. Like the Blattella germanica common in Europe and the Blattella asahinai common in Asia. They are sometimes called wood cockroaches.
egg case, eggcase	A sack containing eggs or living babies that are soon to hatch from within. It is usually used when referring to the offspring of roaches. E.g.: One of my Elliptorhina javanica roaches produced an egg case. Synonyms: egg sac, ootheca.
egg sac	A sack containing eggs or living babies that are soon to hatch from within. It is usually used when referring to the offspring of spiders, tarantulas, mantises and stick insects. E.g.: My female Ornithoctoninae sp. Hon-Sej tarantula produced an egg sac! Synonyms: egg case, ootheca.
exuvia	An exuvia (plural exuviae) is the cast-off outer skin of an arthropod after a moult. In some species the exuvia is eaten soon after the moult. Isopods do eat – their white – exuviae.
exuvium	From exuvia + latin neuter suffix -um. The name of our website.
Eucorydia	Eucorydia is a genus of cockroaches endemic in Asia. They are characterized by a metallic greenish-bluish pronotum and sometimes orange markings on the tegmina and/or abdomen. Some selected species are the following: Eucorydia aenea, Eucorydia dasytoides, Eucorydia donanensis, Eucorydia forceps, Eucorydia miyakoensis, Eucorydia tokaraensis, Eucorydia westwoodi, Eucorydia yasumatsui.
European Spiny Isopod	Common name for the isopod: Cristarmadillidium muricatum.

frass	1. Frass is the term given to the droppings/faeces of insect larvae. Frass is commonly associated with wood boring species as often this the evidence of insect activity within a piece of wood. 2. Frass is also a term used by people who rear butterflies and moths to describe the solid excretion of caterpillars.

Gestro’s Pill Woodlouse	Common name for the isopod: Armadillidium gestroi.
Giant Canyon Woodlouse	Common name for the isopod: Porcellio dilatatus.
Goliath beetle	Goliath beetles are some of the largest insects in the world both as adults and larvae. It is thought that Goliath beetles are the heaviest of all the insects. Larvae can weigh as much as 100 grams and adults 50-60 grams, the adults can also reach 12 centimetres in length. Goliath beetles are a subfamily, the Cetoniinae, within the Family Scarabaeidae (the Scarabs). The beetles are native to tropical regions of Africa. Adult beetles feed on plant sap or fruit but little is known about the larvae which can feed for many months before pupating. It is thought the larvae feed on rotting wood in the wild but, evidence from rearing these beetles in captivity, suggests they require more protein in their diet than other scarab beetles.
Granulated Pill Woodlouse	Common name for the isopod: Armadillidium granulatum, and its varieties / color morphs: A. granulatum ‘Lemon’, A. granulatum ‘Magic Potion’, A. granulatum ‘Naranjito’, A. granulatum ‘White Pearl’, A. granulatum ‘White Pearl Koi’.

Harvestman	cf. Opiliones – eight-legged invertebrates within the Class Arachnida.

imago	Imago is the name given to the adult stage of an insect. It is in the adult stage that insects reproduce. In winged species it is almost always the imago that has wings. However, mayflies have a fully winged subimago (preadult).
instar	Instar is the name given to the developmental stage of an arthropod between moults. For example, after hatching from the egg and insect is said to be in its first instar. When the insect moults it is then a second instar and so on. Instar can be used for insects undergoing complete and incomplete metamorphosis. For example, a butterfly caterpillar can go through several instars before pupation.
Insular Pill Woodlouse	Common name for the isopod: Armadillidium insulanum.
Intermixed Pill Woodlouse	Common name for the Malaysian isopod: Armadillo intermixtus.
invertebrate	Invertebrates are animals without a backbone. Invertebrates include many different phyla such as arthropods (insects, spiders, crustaceans), annelids (worms) and echinoderms (starfish).

larva	A larva (plural larvae) is the juvenile form of an insect. The larva often has a different appearance to the adult and may possess bodily organs that the adult insect does not possess (and vice versa). Larvae need to undergo metamorphosis to reach the adult stage. This separation of larva and adult often means that adult and young do not compete for food. For example, the caterpillar of a butterfly may have a very specific foodplant on which it feeds and the adult drinks nectar from flowers. Different types of insect have other names for their larvae, for example, caterpillars are the larvae of butterflies and moths. For insects that undergo incomplete metamorphosis the larvae are also called nymphs.
leaf insect	cf. Phasmatodea – the Stick and Leaf insects (Order Phasmatodea) are insects well known for their camouflage. They are commonly kept as pets.
Little Pill Woodlouse	Common name for the isopod Venezillo parvus and its varieties/color morphs: Venezillo parvus ‘Dalmatian’ etc.
Little Sea Pill Woodlouse	Common name for the isopod: Cubaris murina. and its varieties/color morphs: Cubaris murina ‘Mandarin’, Cubaris murina ‘Papaya’.

Maculated Dryad Pill Woodlouse	Common name for the isopod: Dryadillo maculatus.
manca	The post-larval juvenile in some crustacean species. The new-born isopods (most of them white). Plural: mancae.
mandibles	Mandibles are the paired jaws of some insects and other arthropods. They are sometimes referred to as simply ‘jaws’. They operate in a sideways fashion and are used for gripping, biting and cutting.
mantis	cf. Mantodea – the Mantodea (or Praying mantids) are an Order of predatory insects. Praying mantids get their common name from the stance they commonly adopt.
Marmorated Pill Woodlouse	Common name for the isopod: Armadillidium marmoratum.
maxilliped	Anterior thoracic limb (one, two, or three) modified to act as mouth part, its body segment usually fused to cephalon.
maxillula	The second mouthpart and fifth cephalic appendage. In the Janiroidea, it consists of two setose lobes: a large outer lobe armed with robust, tooth-like setae; and a smaller inner lobe with only one setae. Plural maxillulae.
millipede	cf. Diplopoda – the Diplopoda are a group of arthropods more commonly known as millipedes. Millipedes mean having a thousand legs. Actually not, just used to differentiate them from centipedes, which have much less pairs of legs.
mollusc	The Molluscs are a Phylum of invertebrates. Molluscs are the second most numerous (in terms of species) animals on the planet, the arthropods are the most numerous. Molluscs are soft bodied organisms but some, snails for example, have a hard shell. Slugs and snails are some of the most well known molluscs and they belong to the Class Gastropoda within the Phylum Mollusca.
morph	A ‘morph’ is the name given to specific groups of arthropods that are all of the same species but differ in appearance. For example, the isopod Porcellio scaber ‘Ghost’ is a morph created from the common Porcellio scaber. They are not to be found in the wild, they are only man-made morphs.
moulted skin	cf. exuvia – the cast-off outer skin of an arthropod after a moult.
multivoltine	A multivoltine species is a species having several broods or generations in a year.
mutation	Mutation in arthropods is a phenotypical variation within the same species or subspecies. Mutation does not appear in all Orders of arthropods. For example the Order Blattodea (roaches), the Class Diplopoda (millipedes) is expressing shows much less mutation. On the contrary, the Order Isopoda shows a great plethora of mutations within the same species / subspecies.
myriapoda	The term Myriapoda was previously used as the name for the group of arthropods containing the centipedes and millipedes. Myriapoda is an old term as taxonomists now separate the centipedes and millipedes into two separate groups: ▪ Chilopoda – Centipedes ▪ Diplopoda – Millipedes The term Myriapoda should not be used.

Nosy Pill Woodlouse	Common name for the isopod: Armadillidium nasatum.
nymph	In entomology nymph is the larva of certain insects. It is used for the offspring of mantises and cockroaches. Plural nymphs. E.g.: I have had nymphs from my Eucorydia yasumatsui roaches!

Painted Pill Woodlouse	Common name for the isopod: Armadillidium pictum.
Pallas’s Pill Woodlouse	Common name for the isopod Armadillidium pallasii and its varieties/color morphs: Armadillidium pallasii ‘Orange’, etc.
Panarthropoda	Panarthropoda is a proposed animal clade containing the extant phyla Arthropoda, Tardigrada (water bears) and Onychophora (velvet worms).
paratype	cf. Type specimen – a specimen that acts as the name bearer for a species.
parthenogenesis	Parthenogenesis is a form of asexual reproduction whereby offspring are produced without the embryo being fertilised by a male. There are a reasonable number of species of insects and crustaceans that can reproduce parthenogenetically but perhaps the most well known is the Indian or Laboratory stick insect (Carausius morosus). In this species, like most other parthenogenetic species, the females lay unfertilised eggs which hatch into females which also lay unfertilised eggs and so on. The dwarf white isopods (Trichorhina tomentosa) are also parthenogenetic.
pedicel	The pedicel is the thin structure that connects the thorax and abdomen. The pedicel is most visible in the Hymenoptera as the pedicel is often quite long and gives Hymenoptera their distinctive thin ‘waist’. Also, the dwarf spider Ostearius melanopygius has also an extremely thin pedicel.
Peracca’s Pill Woodlouse	Common name for the isopod: Armadillidium peraccae.
Phasmatodea	Phasmids are medium to very large (30-300mm) insects. These include the stick insects and the leaf insects. Stick insects are usually very thin and elongated. In contrast Leaf insects are often very flat and wide, thus more closely resembling leaves rather than sticks. Many species are wingless but, when wings are present, the fore wings are shortened and hardened. The hind wings are membranous. The legs are often very thin and can be held almost flat against the body of the insect. Some species have brightly coloured hind wings which can be ‘flashed’ to scare away predators. Other species, such as the American Walking Stick (Anisomorpha bupestroides) and to a lesser extent the Pink Winged Stick insect (Sipyloidea sipylus), have a defensive chemical spray which can cause temporary blindness and considerable pain to humans.
phenotype	In genetics, the phenotype (from Ancient Greek φαίνω (phaínō) ‘to appear, show’, and τύπος (túpos) ‘mark, type’) is the set of observable characteristics or traits of an organism. The term covers the organism’s morphology (physical form and structure), its developmental processes, its biochemical and physiological properties, its behavior, and the products of behavior. An organism’s phenotype results from two basic factors: the expression of an organism’s genetic code (its genotype) and the influence of environmental factors. Both factors may interact, further affecting the phenotype. When two or more clearly different phenotypes exist in the same population of a species, the species is called polymorphic.
pincers	cf. Chelae – pincers or claws at the end of arachnid or crustacean appendages.
pitfall trap	A pitfall trap is a device used to trap insects that are active on the ground surface. Pitfall traps usually consist of a beaker that is buried so that the lip of the beaker is level with the ground surface. The trap is then left and the entomologist returns to it at a later date to inspect ‘the catch’. Insects reaching the lip of the beaker slip and fall in and are then unable to climb back out.
Plain Pill Woodlouse	Common name for the isopod: Armadillo officinalis.
playing dead	cf. Thanatosis – the behaviour of feigning death, usually to deceive a predator.
pleopod	A forked swimming limb of a crustacean (isopod), five pairs of which are typically attached to the abdomen. Plural: pleopods.
pooter	A pooter uses suction to collect small invertebrates without harming them. It consists of a collection vessel (often a plastic or glass jar) with a tight fitting lid. The lid has two holes in it and a tube inserted into each hole. One tube has a fine mesh over the end inside the jar. The entomologist sucks on the open end of the tube that has the mesh at the other end. At the same time the end of the second tube is aimed at an invertebrate. The suction draws the invertebrate down the second tube and in to the collection vessel. The fine mesh on one tube prevents the entomologist swallowing any invertebrates.
Porcelain Woodlouse	Common name for the isopod: Trichorhina tomentosa. Another common name is: Dwarf White Isopod.
Porcellio	Genus of isopods in the family Porcellionidae, usually more elongated than Armadillidium isopods. Currently (May 2023) consisting of 301 accepted species.
Praying Mantis	cf. Mantodea – the Mantodea (or Praying mantids) are an Order of predatory insects. Praying mantids get their common name from the stance they commonly adopt.
pronotum	The pronotum is a prominent plate-like structure that covers all or part of the thorax of some insects. The pronotum covers the dorsal surface of the thorax. For example: The pronotum of the male Lucihormetica verrucosa roaches has two warty orange spots that in wild specimens they glow in the dark.
pseudoscorpion	Pseudoscorpions are very small arachnids (most are less than 8mm in length). Pseudoscorpions possess pincers (chelae) at the end of their palps and it is these that make them resemble true scorpions. Pseudoscorpions do not possess a tail and sting and are harmless to humans.
pudding	An Armadillidium klugii variety with duller colors: Armadillidium klugii ‘Pudding’.
puddling	Puddling is the term given to the aggregation of some insects on wet soil or dung to obtain moisture and nutrients. Puddling is most commonly seen in butterflies with large numbers of individual insects gathering at the edge of puddles, on wet soil, on dung or on carrion. The insects use their proboscis to obtain moisture and also other nutrients and salts. Except butterflies, other insects have been observed exhibiting puddling behaviour.
pupa	The pupa (plural pupae) is the third stage in the life cycle of insects undergoing complete metamorphosis. The four stages are: 1. Egg 2. Larva 3. Pupa 4. Imago/adult Although the pupa might appear to be an inactive stage, inside the pupa the larval body of the insect is being broken down and the body of the adult insect is then formed. During pupation the insect is often completely sessile (incapable of movement) although in some species limited movement is possible. The insect is quite vulnerable at this time and so many choose to pupate out of sight from predators (such as underground) or create a camouflaged cocoon around their pupae. The name pupa comes from the Latin for doll.

Taranga’s Reclined Pill Woodlouse	Common name for the New Zealand isopod: Cubaris tarangensis.
telson	1. The telson (from Ancient Greek τέλσον ‘headlands, limit’) is the posterior-most division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment of the arthropod body, or an additional division that is not a true segment on account of not arising in the embryo from teloblast areas as other segments. It never carries any appendages, but a forked “tail” called the caudal furca may be present. The shape and composition of the telson differs between arthropod groups. 2. Telson is a genus of cyclopoid copepods in the family Telsidae.
thanatosis	Many species of insect and also crustaceans, when they feel threatened by a potential predator, will display a behaviour known as thanatosis (or ‘playing dead’). The insect will often fall to the ground and tuck in any protruding legs or antennae. The insect will remain like this for some time, even when prodded or poked by the predator. Some time after the predator has lost interest the insect will start moving again and make its escape. Thanatosis is displayed by many animals (including some mammals and reptiles) and, amongst the insects and also some isopods, it is commonly found among the beetles – ladybirds are particularly good at ‘playing dead’. It comes from the greek word θανάτωσις meaning the act of dying (root word in greek: θάνατος [death]).
Therea	Therea is a genus of crepuscular cockroaches, currently (September 2023) comprising 8 accepted species. These species are: Therea bernhardti, Therea defranceschii, Therea hyperguttata, Therea irreperta, Therea nuptialis, Therea olegrandjeani, Therea petiveriana, Therea regularis. They are found on the ground in dry areas and include some species that are popular as pets.

Onychophora	Commonly called velvet worms, are panarthropoda with soft body and many legs, of the phylum Onychophora. It’s an ecdysozoan organism with tiny eyes, antennae, multiple pairs of legs, and slime glands. There are some velvet worms that can be kept as pets (Epiperipatus barbadensis). Velvet worms have a velvety texture, waterproof skin, a graceful motion and some of them have amazing colors as well. Such as some rare Australian velvet worm species with blue and purple colors, that are truly mind-blowing. They are not actually worms however, it’s just a name given to describe their characteristics and appearance.
ootheca	A type of egg mass made by any member of a variety of species including mollusks, mantises, and cockroaches. Synonyms: egg case, egg sac.
Opaque Pill Woodlouse	Common name for the isopod: Armadillidium opacum.
ovoviviparous	Animals whose eggs hatch inside their body. Including some reptiles and some cockroaches.

queen	The Queen is the only female within a colony of social insects that can reproduce. These include bees, wasps, ants and termites.

Reduviidae	cf. Assassin bug – insects in the Order Hemiptera (True bugs) that feed on the bodily fluids of other animals. Large Assassin bugs are also kept as pets. Some of them feed only on millipedes.
Rhinoceros beetle, Rhino beetle	Rhinoceros beetles are some of the largest beetles in the world. Rhinoceros beetles are a subfamily, the Dynastinae, within the Family Scarabaeidae (the Scarabs). Adult beetles feed on nectar or sap. The larvae commonly feed on rotting wood. Rhinoceros beetles get their name from the horns possessed by the adult male beetles. These horns are used when males fight for mates.
roach	cf. Blattodea – an Order of insects that contains the cockroaches. Cockroaches are some of the most despised insects despite there being only about 25 species that are considered pests.
Robinson trap	cf. Moth trap – a device used to attract and capture moths which can then be studied.
Rose chafer	cf. Scarab – a family of beetles that have distinctively shaped antennae and are often metallic in colouration.
Ruffo’s Pill Woodlouse	Common name for the isopod: Armadillidium ruffoi.

saltatorial	Saltatorial is a term used to describe the legs of some insects and other invertebrates that are modified for jumping. Grasshoppers and crickets have saltatorial hind legs. The legs are much larger than the other two pairs of legs and allow these insects to jump a considerable distance.
Sandstone Pill Woodlouse	Common name for the isopod: Armadillidium scaberrimum.
saprophage	cf. Detritivore – detritivores are animals whose diet is primarily composed of decaying organic matter.
Scarab	The Scarabs are a large family of beetles, estimates suggest that there are more than 30,000 species of beetle in this family. The beetles can be brightly coloured (often with a metallic sheen to their exoskeleton) and have distinctive antennae. The Scarabs include the dung beetles and these were a significant feature of life in Ancient Egypt. The rolling of dung by these beetles was seen to be representative of the rolling of the sun across the sky.
Scorpion	Scorpions are predatory arthropods within the Order Scorpiones and the Class Arachnida. Scorpions are some of the most familiar of arthropods. Even if scorpions do not live in your part of the world you are almost certain to know what they look like. Scorpions have a very distinctive body structure as they have two long pedipalps ending in chelae (pincers) and a sting attached to a tail that is often curved over the body of the animal when it is threatened. Although scorpions are often feared by humans only around 20 species out of 1,500 have venom that is potentially lethal to humans.
semelparous	A species is considered semelparous if it is characterized by a single reproductive episode before death. For example Armadillidium tunisiense isopods are considered to be semelparous. Opposite of semelparity is iteroparity.
semivoltine	A semivoltine species is a species having a brood or generation less often than once per year.
seta	A cuticular hair or outgrowth arising from the outside of the exoskeleton, or having recognizable basal articulation. Plural setae.
Simon’s Pill Woodlouse	Common name for the isopod: Armadillidium simoni and its varieties: Armadillidium simoni ‘Villeneuve-Loubet’, etc.
Sordid Pill Woodlouse	Common name for the isopod: Armadillidium sordidum.
Southern Pill Woodlouse	Common name for the isopod: Armadillidium depressum and its varieties/color morphs: Armadillidium depressum ‘High Contrast’, Armadillidium depressum ‘Magic Potion’ etc.
spinneret	A spinneret is a silk producing organ possessed by spiders and some insects (often caterpillars of butterflies and moths). Spinnerets are tubular or conical structures and silk is produced in liquid form at the tip. When exposed to the air the silk forms a filament and the spider or insect draws out the silk into a thread. The silk is then used to create a web or covering for a cocoon.
spiracle	1. A pore or opening used (especially by arthropods and some fish) for respiration. 2. Any small aperture or vent for air or other fluid.
Split Clown Isopod	Common name for the isopod: Armadillidium klugii ‘Split’.
springtail	cf. Collembola – the Collembola/springtails are one of the three non-insect hexapod classes of invertebrates. There are springtails that jump, and other species that cannot jump.
Stick insect	cf. Phasmatodea – the Stick and Leaf insects (Order Phasmatodea) are insects well known for their camouflage. They are commonly kept as pets.
symbiosis	A symbiotic relationship is one that exists between two (or more) different species. Several different categories of symbiotic relationship can exist: ▪ one species benefits but the other species suffers (also called Parasitism) ▪ one species benefits and the other is unaffected (also called Commensalism) ▪ both species benefit (also called Mutualism)

univoltine	A univoltine species is a species having a brood or generation in a year. Some species of cockroaches (Therea olegrandjeani) are univoltine.
uropod	Either of the two posterior abdominal appendages of the isopods, lobsters, shrimps and some other crustaceans. Plural: uropods.
urticating hairs	Urticating hairs are possessed by some arachnids (specifically tarantulas) and insects (most notably larvae of some butterflies and moths). The hairs have barbs which cause the hair to work its way into the skin of a vertebrate. They are therefore an effective defence against predation by mammals. One of the more well known moth larvae that possess urticating hairs are those of the Pine Processionary moth (Thaumetopoea pityocampa). The Pine Processionary moth are a major pest in pine forests/plantations and the caterpillars form silken nests within the tree. The caterpillars form characteristic processions with each caterpillar following the previous one (head to tail) from a tree to an area where they burrow underground and pupate. Although they use pheromone trails the caterpillars rely on touching the hairs on the rear of the preceding caterpillar to form the procession.

velvet worm	see Onychophora above ^
Velvety Pill Woodlouse	Common name for the isopod: Eluma caelata.
Versicolored Pill Woodlouse	Common name for the isopod: Armadillidium versicolor.

Walking stick	cf. Phasmatodea – the Stick and Leaf insects (Order Phasmatodea) are insects well known for their camouflage. They are commonly kept as pets.
WC	WC (Wild Caught). An animal whose parents were wild, and the animal itself lived in the wild until it was caught. Some of those animals may have travelled long distances, have internal parasites, and will likely have scars from old injuries sustained whilst it lived in the wild. They are also likely to be stressed when first placed into an enclosure and some species never take well to captivity, they might have trouble reproducing, and even refusing to eat.
Werner’s Woodlouse	Common name for the isopod: Porcellio werneri. Another common name is Greek Shield Isopod.
White Pill Woodlouse	Common name for the isopod: Armadillidium album.

xylophagous	Xylophagous animals are those that feed almost exclusively on wood. Insect examples of such animals include furniture beetles and death watch beetle.

Yellow-bordered Woodlouse	Common name for the isopod: Porcellio flavomarginatus.