3.1 Invertebrates

There are four different species of wood ant in Scotland. The Scottish wood ant and the hairy wood ant are both found in coniferous woodlands. The narrow-headed and red robber ant are both found on the edges of woods.

Identification of wood ants

Features common to all wood ant species, differentiating from other ant species:

• Black head and abdomen with a red thorax.
• Build a large, thatched mound as a nest in which to live.
• They are larger than other ant species in the UK, up to 10mm.

Differentiating between UK wood ant species (requires a hand lens):

• Narrow headed wood ant: deep notch at back of head, unique to this species.
• Scottish wood ant – Sparse, short hairs around top of head which do not reach the eyes; hair along top of thorax is sparse and short compared to hairy wood ant.
• Hairy wood ant: short hairs on top of head reaching the eyes; hairs forming continuous line along top of thorax to waist which are longer than those of southern red and Scottish; long hairs emerging from sides of thorax when viewed from above.
• Southern red wood ant; shows absence of hairs around top of head in between eyes; few short hairs long top of thorax.

Members of the Pentatomoidea, a superfamily within the order Hemiptera or ‘true bugs’, defined by their sharp, straw-like mouthparts that are usually used for piercing plant tissue and sucking up sap, though some bugs prey on other invertebrates

There are approximately 40,000 species of spider around the world, only one of which is not a carnivore! In the UK we have 600 species of spider

Identification

A spider’s body consists of two parts, the front cephalothorax and the rear abdomen.

They have eight legs. Most species have eight eyes on the front of their head, though some have only four.

Their mouthparts have fangs with which they trap their prey and inject a fatal venom. This venom first paralyses the prey and then turns their insides into a liquid soup, which the spider then sucks up through their powerful mouths.

Spiders also have two appendages at the front of their body that are often mistaken for extra legs. These are in fact called palps and function like a pair of arms or hands helping the spider grab its prey. These palps are a great way to determine the sex of your spider. If the palps look like they have boxing gloves on the end of them, then your spider is male; if there are very small swellings, then your spider is female. These ‘boxing gloves’ are used by the male spider to show sexual interest in a potential mate. They are also used as ‘sexual pipettes’ to inject sperm into the female.

Both centipedes and millipedes are members of the myriapod phylum, meaning ‘many legged’. Within the UK there are 57 species of centipede, and around 50 millipede species.
Despite their names they do not have 100 or 1000 feet, the exact number varying with the species. In the UK centipedes range from 15-101 pairs of legs (always an odd number) and millipedes having between 20-200 pairs.

Identification

Differentiating centipedes and millipedes:

• Centipedes have one pair of legs per body segment, millipedes have two pairs.
•    Centipedes’ bodies are often flattened, with the legs arranged out to the side, millipedes are usually cylindrical with the legs arranged beneath the body.
• Both are variable in size and colouration with species. Centipedes can range from browns to reds and yellows.
• Centipedes often have long antennae, compared to the shorter antennae of millipedes, and have elongated legs at rear similar in length to antennae, a feature lacking on millipedes.
• Head of centipedes is usually distinct from rest of body, whereas millipedes’ head is more integrated into body.

Identifying common species:

•  Common Centipede: up to 3cm long; brownish-red body; 15 pairs of legs (this is a common feature of all Litobius genus, the stone centipedes).
• White-legged snake millipede: 50 pairs of legs; shiny black, long, cylindrical body; white legs which contrast against the dark body.
• Flat-backed Millipede: 20 pairs of legs; approx. 25mm long; orange-brown body; flattened body more resembling a centipede.

Behaviour and interesting facts

• Centipedes produce venom, like spiders do, to either defend themselves or to subdue prey as they are carnivores feeding on other centipedes and invertebrates.
• If a centipede loses a leg, it can grow a new one to replace it.
• Common centipedes can live for up to three years.
• Millipedes are detritivores, like worms, that feed on dead matter. This makes them important soil makers, using their strong mouthparts to eat dead leaves and other vegetation which, through their droppings, they turn into nutrient rich soil.
• Millipedes need to eat almost ten times their own body weight in food each day due to the low nutritional content of their food.
• Millipedes defend themselves from some but not all predators by creating chemicals that smell or taste nasty. Some also roll themselves up in a spiral to protect their softer underparts with their more robust uppermost exoskeleton.
• Millipedes have simple eyes capable of detecting light and dark only. They can live up to 11 years in captivity.

Millipede – https://commons.wikimedia.org/wiki/File:Millipede_(43153282620).jpg

There are 26 different species of native earthworms in the UK. Aside from being a food source for many other larger animals, earthworms are a keystone species in most habitats, recycling dead and decomposing plant material back into fertile soil, though most of the earthworm’s nutrition comes from the fungi and associated decay, rather than dead plant matter itself

Identification

• UK earthworms species range in length from 1-30 cm (the longest UK specimen on record was 40cm!)
• Earthworms have a legless, long, thin body, divided into segments.
• Mature specimens have a wider, paler, slightly raised series of segments called a saddle or clitellum (only about half the worms you will find will be mature enough to have this feature).

There are 24 different types of bumble-bee in the UK. They are social species, living within nests.
Bees, like wasps, butterflies, and moths, are responsible for the pollination of many of our plants. They do not make honey as they do not need to store food for the winter.

Identification

• Appearance will vary within a species by the caste it occupies within the nest.
• Bumblebees are overall hairier than honey or solitary bees, and average between 1.5 to 2.5cm long.
• Colour varies between species, commonly showing a degree of yellow and black banding within the body.
• Show one large pair of transparent flight wings, not contained within a hard ‘shell’.
• Antennae are not rigidly angled, unlike ants, and can be straightened.
• Tree Bumblebee (female): ginger thorax; white tail; occupy woodland, gardens and open countryside.
• Red-tailed Bumblebee (female); Overall jet black with a bright red or orange-red tail
• White-tailed Bumblebee: yellow collar, yellow abdominal band and white tail.
• Common Carder Bee: overall shades of brown, with no white tail, ranging from ginger to sandy brown.

The peacock butterfly is one of 59 species of UK butterflies, most of which are resident year-round, with three species regularly visiting and breeding in, the UK

Identification

• Overall colouration varies with species and differs on upper and lower surfaces of the wing.
• Two clubbed antennae (unlike moths that do not have the ‘clubs’ at the end of their antennae) for smelling, and balance.
• Four wings, a larger upper pair and smaller lower pair, covered in coloured scales.
• A long thin proboscis (mouth parts) for sipping nectar rolled up under the front of the head or uncurled when inserted into flower.
• Peacock Butterflies: overall red and black colouration; four ‘eye-spot; wing underside mottled brown; wingspan 63-69mm, upper end of UK species
• Small Tortoiseshell:  red-orange wing, with black and yellow markings. Wings fringed by blue spots around edge of wings.
• Orange-tip: white wing upper surface; males with orange tips to forewings and light-grey wing tips; females with grey-black wing tips, lacking orange.
• Large white: White wings with black tips to forewings; females have two black spots and dash on each forewing.

Slugs and snails are gastropods (meaning stomach-foot). They have an un-segmented soft body. Gastropods are part of the mollusc phylum that includes whelks and mussels, squids and octopuses. Here we are concerned with terrestrial (land based) species, primarily slugs and snails.

Identification

• Slugs and snails have an unsegmented soft body. Differentiated by the presence or absence of a hard external shell, which snails have, and slugs do not.
• Slugs and snails have two pairs of tentacles, one responding to light, the other to smell.
• The body, or ‘foot’ is mostly longitudinally ribbed in appearance, behind a smoother and tougher mantle at the front of the body, with a breathing hole, or pneumostome, on the right side of the mantle.  
• European black slug: black, though immature individuals can be brown or ivory grey; 10-15cm in length.
• Leopard slug: overall grey-brown colour, with black spotting arranged along length of the body.
• Common garden snail: shell height 25-35mm; shell is thick with a rough, wrinkled surface and 4.5–5 whorls; shell usually pale brown, occasionally yellow; shell marked with up to 5 spiralling bands, variably flecked with white or yellow brown and having lateral yellow zig-zagging lines.
• Banded snails, Cepea spp.: shells bright coloured with brown, yellow or white stripes, common UK species differentiated by colouration of shell lip being either brown or white.

Interesting facts

• Black slugs can take up to a year to reach maturity. They are hermaphrodite, and though they prefer to find one or more mates, they can self-fertilise. They can lay up to 150 eggs at a time, in dark moist places such as under moss. Slugs generally live up to two years.
• Slugs evolved from snails, the shell being lost perhaps allowing the organism better mobility and access to tighter spaces, though this left the slug more susceptible to drying out.
• Slugs and snails help plants regenerate by moving plant matter around and thereby helping with seed dispersal.
• Slugs and snails have a toothed tongue, called a radula, which has up to 27,000 teeth! This serrated tongue is used to break down food into smaller pieces to be further broken down and digested by enzymes. As detritivores they recycle decaying matter into more usable fertile soil. They in turn also provide a food source for badgers, foxes, hedgehogs, slow worms, and various birds.

This is the largest group of animals in the world! With over 370,000 different species worldwide, beetles make up a quarter of all animals on the planet and exist in every habitat other than the marine and polar regions! However in the UK we have only 4,100 species.

Identification

• As insects, beetles have six jointed legs, three body parts (head, thorax and abdomen) and a hard exoskeleton including hard elytra, (forewings that form a hard shell covering flight wings where present) which meet down the middle of their abdomen.
• Violet ground beetle. Up to 35mm long; overall black colouration with violet iridescence all over, especially around edge of elytra which is almond shaped; elytra are fused, and beetle is unable to fly; antennae are ‘beaded’, not consistent in diameter along their length.
• Woodland dor beetle. Between 12-20mm long; shiny black all over, with iridescent purple on underparts only; abdomen short and oval; antennae having three pronged ‘combs’ at tip; pointed keels on legs; elytra are dotted into longitudinal groves.
• Tiger beetles: These beetles come in a variety of different colours and belong to a large family called ground beetles. Tiger beetles are ferocious hunters, feeding on spiders, ants and caterpillars. They are also one of our fastest insects on the ground (though they can fly). There are 2,600 known tiger beetle species worldwide. The fastest known tiger beetle can run at 9km per hour (5.6mph). This is the equivalent of a human running 480 miles (770kmh) per hour!

Sometimes known as pill bugs or slaters, there’s more to a woodlouse than meets the eye. Woodlice are tough little creatures that play a vital part of the ecosystem. They can be found almost everywhere and especially like dark, damp places. Be sure to look under loose stones, bricks or old logs and leaf litter.

Identification:

• Woodlice have a hard exoskeleton made up of several ‘plates’.
• They have seven identical pairs of legs, and belong to a group of animals called isopods, which means ‘identical legs’.
• They have antennae for feeling their way in the dark and a cluster of eyes used to detect darkness and light.
• At the back of the woodlouse there are what looks like a further four antennae (there are in fact only two of these but they fork and therefore look like they are four). These antennae are used for feeling their way around but they also act as the distributor of a nasty smell if the wee creature feels threatened.