AHEAD Trivia Quiz

Answer: Spitting spider

The spitting spiders of the Scytodes genus do not build webs to catch prey. Instead they spit a sticky glue at the target in a zig-zag pattern to trap the prey against a substrate. The glue congeals on contact. It appears not to contain venom, although it is made in the same gland used for venom production. Once trapped on the ground, a venomous bite is used to kill it.

When subdued, the prey is wrapped in silk. Sometimes the spider will pursue a prey spitting silk at it.

Answer: Bombadier beetle

There are some 500 species of bombardier beetle which are mainly known for their explosive defence mechanism. The beetles separately store aqueous hydrogen peroxide and foul-smelling hydroquinones in glands. When threatened, a valve opens to allow the chemicals to mix in a reaction chamber using catalase enzymes to create a highly exothermic reaction.

The result is a near-boiling toxic liquid which, due to the pressure build up, is released in a series of explosive pulses towards the predator. Around 70 such pulses occur in a fraction of a second. This equates to a rate of 500 pulses per second. The African bombardier beetle has an external gland opening which can swivel through 270 degrees, allowing it to spray with accuracy.

Answer: Cone snail

The slow-moving cone snail is a carnivore targeting marine worms, small fish and molluscs (including other cone snails), although people have been killed by the venom from some of the larger fish-eating species. Of around 750 species, around 100 target fish. Several hunting strategies have evolved which may be classed as 'taser and tether', 'net engulfment' and 'strike and stalk'. The 'taser and tether' technique is described.

A radula tooth is used as the harpoon. It is hollow, barbed and attached to the tip of the radula. Spares are stored in the radula gland. When a target is detected (mainly by chemosensing), a flexible tube is extended towards it and hydrostatic pressure is used to release the venom-loaded harpoon. Once paralysed, the radula with the prey is retracted into the mouth of the snail.

Answer: Colobopsis ants

The binomial name Colobopsis explodens is a bit of a clue. It is a species of ant found in South-east Asia and is one of several ant and termite species to exhibit this combat mechanism. It has been termed autothysis. Termites tend to use it to block tunnels as a defensive strategy. Although the individual is destroyed, the colony will likely survive and pass on this genetic trait.

In the case of Colobopsis ants, the worker ant may clamp itself onto an invading arthropod and then use its muscles to rupture its gaster explosively, coating the target with sticky toxic chemicals. The Malaysian exploding ant (Colobopsis saundersi) has two oversized mandibular glands running the length of its body and containing the toxins. Rupturing the gaster bursts these glands. It is used as a territorial defence and also a defence against predation.

Answer: Jellyfish

The phylum Cnidaria takes its name for the cnidocyte cells which deliver the sting. The phylum includes jellyfish, corals, sea anemones and hydrae. The cnidocyte is a one-time use cell. The cell contains an organelle with a coiled tubule within which is stored inside out.

A combination of chemo-sensor and mechanoreceptor triggers the sting. Osmotic pressure is used to evert the tubule in a few microseconds (implying acceleration of around 40,000 g) which penetrates the target and delivers the toxin. Mass delivery of stings can overwhelm the target.

Answer: Archerfish

The archerfish is a family of tropical fish consisting of ten species which has developed the technique of shooting down land-based insects with jets of water. Adults are remarkably accurate, hitting insects at first attempt up to 3 metres (10 ft) above the surface of the water. Usually spitting at an angle of 74 degrees, they can compensate for the refraction of light as it passes through the air-water interface for spitting angles between 45 and 110 degrees.

The water is shaped in the mouth so that the water at the rear catches up with the leading edge of the water as it reaches the target, adjusted for range.

Answer: Velvet worm

Looking a bit like worms with stub feet or caterpillars, there are some 200 species of velvet worm varying between 0.1 and 22 cm (0.04 and 8.66 in) in length. On their third head segment they have two openings (called oral papillae) either side of the mouth from which the glue-like milky-white slime is produced.

A syringe-like action amplifies a slow muscular contraction to jet two oscillating streams through small openings (50-200 microns). These combine to weave a disordered net which is used either defensively or to snare a prey.

Answer: Horned lizard

Some North American horned lizards (Phrynosoma genus) include blood squirting amongst their defensive measures, a strategy of last resort. Camouflage is the main defence, coupled with remaining motionless. Puffing up to appear more horned and larger is another strategy. Several species can squirt an aimed stream of blood from the corners of the eyes. Such lizards can rupture these blood vessels by restricting the flow of blood leaving the head.

The blood acts as a distraction and is foul-tasting to canine and feline predators, possibly due to a diet that includes quantities of venomous harvester ants.

Answer: Nasute termites

Found in nasute termites, the soldier caste have a horn-like projection on their heads which contains the duct from a gland, the setup being called a fontanellar gun. The gland material is expelled through the horn by chemical reaction activated when the mandibular muscles are contracted. The sticky resinous 'bullet' consists of three terpenes, one of which acts as an alarm signal resulting in multiple fontanellar guns being deployed to immobilise an intruder (such as an ant or another termite).

As the soldier termite is blind, success is possibly achieved through engaging at short range, using vibration and chemical cues, and having dozens of shooters targeting the same intruder.

Answer: Mantis shrimp

Mantis shrimp are carnivorous crustaceans. The species are categorised by the claw shape - spears and clubs being the main ones. The dactyl club type generally smashes the prey with a heavily mineralised club-like appendage. The speed of the strike is such that it creates cavitation bubbles which can cause further damage when they collapse, meaning that the prey is hit twice by a single strike. If the claw misses, the shock wave alone may stun the prey. This is the projectile element.

The energy for the strike comes from the slow contraction of muscles loading elastic energy into a saddle-shaped mechanical spring. A latch-like tendon system releases the energy for a strike.