Rhinoceros iguana

The rhinoceros iguana (Cyclura cornuta) is a native of the Caribbean, and in particular the islands of Hispaniola (Haiti and the Dominican Republic) and Puerto Rico.

It is a large animal, measuring up 1.2 metres (4 feet) in length. It is characterized by several enlarged raised scales on the snout that look like horns. Males are larger than females, with larger horns and crests.

Rhinoceros iguanas walk ponderously with the head held up, but can run at speed when threatened. It will also bite and thrash its tail to defend itself. It is highly territorial.

Food consists of leaves and fruits.

Females will lay anything from two to twenty eggs in a burrow, which will be closely guarded.

Habitat destruction is a threat to the species, as are predations from non-native animals including dogs, rats, pigs and mongooses.

© John Welford

Anteaters versus ants

One might think that anteaters, such as the giant African Pangolin, have an easy life. They eat ants and the plains are full of anthills just waiting to be raided for their contents. However, ants have their own ways of making things uncomfortable for anteaters.

When a mound has been slashed open the ants will swarm out in their thousands to mount a stern defence. Many will perish in the attempt, being caught on the anteater’s long sticky tongue and swallowed whole, but others will try to penetrate the monster’s eyes and nostrils. The anteater will get round this by shutting its eyes with its particularly thick eyelids and using special muscles that close its nostrils.

Even so, the anteater will soon find the experience not to be one worth prolonging and may be forced to give up after having consumed only about a hundred ants. A pangolin can eat up to 200,000 ants in a night, which means that it has to be extremely busy finding ant colonies and grabbing what it can at every opportunity.

There are also ant species that have defences that will dissuade anteaters from even trying their luck with them. These include leaf-cutter ants and army ants, both of which have strong jaws that can give an anteater’s snout a very sharp nip.

The fact that various species of anteater and ant have evolved feeding and defence strategies that put them in balance means that all their species have survived down to the present day. In other words, there are still enough ants to feed the anteaters, but not so many anteaters that all ant colonies are destroyed.

© John Welford

Seduction, lizard style

Female lizards in California have shown that, when it comes to choosing a mate, what matters most is the property he owns rather than any other attribute he might possess!

The lizards in question are side-blotched lizards (Uta stansburiana) that, being cold-blooded, depend on the heat of the sun. They live on rocky outcrops and the most prized site for basking is a boulder that stays illuminated for as much of the day as possible and has crevices underneath it that offer a hiding place should a predator turn up as well as a place where a female can lay her eggs.

The best boulders are subject to intense competition among male lizards, and soon become the property of the alphas in any lizard community. They then get to breed with the most females, which is all to the good in terms of species survival.

However, experiments have been done that show that being an alpha male is not in itself the reason why females will gravitate in his direction. When top-rated boulders are taken away from an alpha and given to a much punier male, the latter suddenly becomes a lot more popular with the ladies, probably much to his surprise.

It would appear that it is not only human females who can be seduced by the best rock in the window!

© John Welford

A particularly nasty wasp

There are several wasp species across the world that have a life cycle that involves them becoming parasites of other creatures. One of these is a Costa Rican wasp (Hymenoepimecis argyraphaga) that targets a particularly formidable spider (Plesiometa argyra).

The spider is large and fearsome, and therefore avoided by just about every other insect apart from females of the wasp. It hovers above the spider then lands directly on its back, where it lays a single egg before making its escape.

The spider is not affected by this visit at first, but in time the egg absorbs nutrients from the host and the larva that hatches from it injects the spider with a chemical that makes it act in ways that it would not otherwise have done.

The night before the larva is ready to pupate, the spider destroys its web, which is not unusual given that many spiders do so as part of their regular behaviour. However, when a new web is spun, it is very different from what went before because its purpose is entirely to benefit the wasp and not the spider.

This web is hardly a web at all, because it consists of strands of strong silk that provide an anchor to nearby plants. When finished, the spider hangs beneath this framework and never moves again.

The wasp larva then eats the spider, and by dawn it is ready to weave its own cocoon which hangs inside the rough web made by the spider. It will then take its time in transforming into an adult wasp, protected inside its cocoon which in turn is safe from ants and the effects of heavy rain thanks to the strong threads that the wasp forced the spider to weave.

Nature has managed to produce some amazingly unpleasant creatures!

© John Welford

Nautilus

The nautilus (Nautilus pompilius) is a remarkable creature that is regarded as a “living fossil” because it closely resembles animals that lived in the oceans between 400 and 65 million years ago. Six species of nautilus have survived to the present day, with that in the photo living in the western Pacific Ocean and in open waters around Indonesia and southeast Asia. It is found at depths up to 500 metres (1,650 feet).

The shell protects the nautilus from predators and buoyancy is provided by gas trapped in the inner chambers. It swims by using jet propulsion – water is taken into the shell cavity and expelled through a tube which can be directed to propel the nautilus in the required direction.

The head sticks out of the shell and has up to 90 tentacles that are used to trap prey that includes shrimps. The eyes of the nautilus are very primitive, being without lenses and working like pinhole cameras.

The nautilus only becomes sexually mature after about ten years, and then produces as few as twelve eggs per year. Having survived for so long, the species has clearly found an environmental niche that presents few dangers and allows for a slow rate of reproduction.

© John Welford

Box jellyfish

You would not want to get too close to a box jellyfish (Chironex fleckeri). It is thought to be one of the most venomous creatures to exist in the oceans and it can kill a person in only a few minutes. 

Fortunately for most of us, it is mainly confined to waters to the north of Australia and eastern Indonesia, but it is plentiful enough at certain times of the year (November to April in northern Australia) to make it necessary to close beaches to the public. 

It is only a small creature – up to 25 cms (10 inches) in size – but its tentacles can extend up to three metres (10 feet) in length. It is possible to be stung without even seeing the jellyfish itself. Its prey is prawns and small fish that swim in shallow water. 

The name comes from the box-shaped transparent body, from each corner of which hangs a bunch of 15 tentacles. The flattened sides of the box contain sense organs that include remarkably complex eyes. 

Should a swimmer be unfortunate enough to be stung, and not be able to get hold of antivenom, the least he or she can expect is excruciating pain and skin damage that can leave permanent scars. Heart failure is entirely possible, as is drowning following loss of consciousness. 

Despite the extreme dangers presented by contact with this animal, some sea turtles are able to eat box jellyfish without suffering any harm.

© John Welford

Wild liquorice

Wild liquorice (Astragalus glycyphyllos) has the alternative name of milk-vetch, from the former commonly held belief that goats that ate the plant would yield more milk.

It grows in scattered location in Great Britain, in rough grassy places on chalk and limestone, but is absent from Ireland. It is a temperate plant that is also found across much of northern and central Europe as far east as the Caucasus.

Wild liquorice is difficult to spot because it often grows among tall grasses and its greenish-cream flowers blend with the colour of its foliage. 

It is a straggling plant that can grow up to 40 inches (100 cm) in height. It has smooth, trailing stems and many hairless leaflets. The stems bend each time they give rise to a leaf, which makes them zigzag. 

The plant flowers in July and August, many flowers being carried on stalks that are shorter than the leaves. The pods are smooth and curved, with a central division such that several seeds are produced on each side of the “wall”.

Wild liquorice is not the plant from which laxatives and food flavourings are produced. However, the root stems of both wild and true liquorice can be chewed – the botanical name glycyphyllos means “sweet stem”.

© John Welford