Wednesday, 24 August 2016

Incredible Invertebrates #03: The insect with the strangest headgear in the world?

First of all, a little update on the wasp nest in the shed - it's got bigger. The shed has now become a hive of activity (pun intended), and the nest itself is now several times its previous size. If you go around the back of the shed and put your ear against it, then you can hear the wasps buzzing in their nest! A few nights ago someone tried to break into our shed, and although they were scared off by the alarm, I imagine if they were not deterred by that, they would be in for a painful surprise! As I said to my dad, we should put a sign on our shed saying, DANGER: GUARD WASPS AT WORK. ENTER AT YOUR OWN RISK.
Anyway, now onto our incredible invertebrate . . .

Bocydium globulare is a kind of treehopper, belong to the suborder Auchenorrhyncha, which are true bugs. Groups and families belonging to this suborder include froghoppers, cicadas, and leafhoppers, as well as treehoppers. The latter contains around 3,200 species, and are found on all continents except for Antarctica. They often have an unusual or large pronotum, which can form spines, or sometimes stranger shapes.
Perhaps the weirdest of the family, however, is the Brazilian treehopper. Before I even begin to talk about this thing . . . just look at it.

This is a model of the Brazilian treehopper, but the real insect looks exactly the same. Please note: this image does not belong to me

This strange insect can be found on Tibouchina plants, and is mostly solitary. Other than that, the information on its behaviour and lifecycle seems pretty limited, but there's plenty of information about its strange headgear.
The ball-like structures are not eyes, despite appearances, but hollow chitinous spheres. But what on Earth could they be for, and why is there that long spine emerging from the back of the structure?
My first thought was something to do with mating. Perhaps sexual selection has led these creatures to evolve more and more elaborate ornamentation? Or it could play a role in males fighting for females, rather like stag beetles.
It turns out, other people have had the same idea, but dismissed it, because usually such strange ornamentation is only present in males of the species. However, in the Brazilian treehopper, both males and females bear this strange headgear.
Bearing this is mind, it seems likely that these true bugs use their crest for defensive purposes. Say, for example, that a bird spots one of these animals, and decides to have a snack. Those strange spines and spheres would make it difficult for it to get a hold on its prey, and even if it managed to get past that, can you imagine swallowing something like this? It would be very difficult, and probably painful.

You may notice from the model that the headgear is covered in strange hairs. The exact purpose of these is not known, but they may serve as an irritant, strengthening its defence mechanism. Another idea is that they could be sensory.

The Brazilian treehopper is not the only strange treehopper. Umbonia crassicornis, the thorn bug, mimics a spine to escape predator's attentions.

By Marshal Hedin from San Diego - Umbonia crassicornis (F Membracidae)Uploaded by Jacopo Werther, CC BY 2.0,
Above: a group of thorn bugs on a branch

 There are many other strange treehoppers, but that's to be discussed another time.

Until next time, keep on the wild side!

Tuesday, 9 August 2016

Incredible Invertebrates #02: the jellyfish that can live forever

First of all, a little update on recent activities. Yesterday I joined the Phoenix group at the Humber Bridge Country Park to see if we could find any Roesel's bush crickets, which are rare in this area of Britain. This species had been sighted nearby, and they are known to travel along verges of railways to new localities, so we thought that it would be worth having a little check for the crickets on Country Park. We tried to pick up their stridulations on bat detectors, but unfortunately we found nothing - it does not mean, however, that the crickets aren't there, only that we haven't found them yet.
While we didn't discover any Roesel's bush crickets, I did find some ants. Rather too many ants, in fact, as these happened to be of the species Myrmica rubra, sometimes called the common red ant or European fire ant. The latter name is rather fitting, as this species, while unable to spray acid as many species can, delivers a very painful sting. Having shoes and trousers full of European fire ants was not a pleasant experience! I was quite surprised that the pain of the stings didn't go off for 2 hours, leaving a dull tingling sensation. During this time, it hurt every time I moved my feet. I had no idea that they had such painful stings!

Anyway, onto our incredible invertebrate. This one has always amazed me, because while some animals can live to old ages (trees even more so), one species takes this a step further: it can, theoretically, live forever.

Turritopsis dohrnii is a species of jellyfish. In its adult form, called the medusa, it is quite small: around 4.5 millimetres wide, and about the same tall. They can have up to 90 tentacles, and their large, red stomach can be seen through their transparent flesh. They feed on tiny organisms, and although they are very difficult to keep in captivity, the one person who has managed it, Shin Kubota in Japan, has cultured his on brine shrimps.

 By Bachware - Own work, CC BY-SA 4.0,

These jellyfish do not look very extraordinary, and do not stand out as something special, being rather small and not overly striking. However, it is their life cycle that is outstanding.
Jellyfish normally have fascinating life cycles, and this species is no different.
Females of the species have gonads in the walls of their stomach, of all places, and this is where they keep their eggs. Not much is known about what happens next, but is thought that the eggs are released into the water, where they are fertilized by sperm. Afterwards, the eggs sink to the seabed where they develop into the larval stage, what is known as a planula larva. They develop into colonies of polyps, called hydroids, which will eventually bud off into multiple tiny jellyfishes. Each one of these juveniles are about 1mm in size, but in a few weeks they will have grown and become sexually mature.
Once these jellyfish are adults, they are known as medusae (singular is medusa), and it is these that we know so well. The next stage in their lives will be to breed, and then . . . death? Invertebrates, after all, have famously short lifecycles, at least in some species. Most jellyfish live no more than a few months, and a few live for only a few hours. But T. dohrnii is the complete opposite. The next stage in its life is not death, but something entirely different.
The medusa's tentacles and body will begin to disappear. It will grow polyps, which will settle down on the seabed, and begin to multiply, forming a hydroid colony - and the adult jellyfish will no longer be an adult, but a sexually immature hydroid colony. It has turned its lifecycle on its head, growing back into its hydroid form - which would normally only exist just after the fertilized egg has hatched into a planula, which would begin to form the polyps. Afterwards it will form more small jellyfish.
This jellyfish has, essentially, bypassed death to revert back to a younger form. It is the equivelant of a human, once becoming old, changing back into a toddler, and then carrying on growing all over again, then repeating the process, again and again.
You will probably see what I'm getting at now. This jellyfish cannot die of old age, and is theoretically immortal. The only things that are stopping it from living forever are predators, strandings, and other causes of death. If for a moment we image that we could remove these things from their habitat, an individual of this species could live forever. Just imagine that: one individual jellyfish living for millions of years, until the end of the world. Though of course it wouldn't be just 1 jellyfish, because when it reverts back to its polyp form, it will grow into multiple young jellyfish. So it is not only immortal, but in the process it can create what is essentially lots of little versions of itself.
This is all incredible, but also speculative. Without solid evidence, we cannot be sure if this species could theoretically live forever - I say theoretically, because as already mentioned, there are predators and natural disasters which could kill the individual. Still, it has been given the rather impressive name of the immortal jellyfish.
As previously mentioned, it is very difficult to keep this species in captivity. Only a Japanese man of the Kyoto University has managed to keep the immortal jellyfish for a long period of time. He has kept them for a few years now, and he has recorded that every 2 years, an individual will have managed to revert itself to a younger form around 11 times.

Longevity seems to be a recurring theme in many marine animals. Some black corals are thought to be around 4,265 years old, and a species of clam called the ocean quahog can live for 507 years, possibly longer. The rougheye rockfish can live for up to 205 years old (although this is not the oldest fish. That goes to Hanako, a koi carp who died at 226 years old. However, if reports are to be believed, koi can live for more than 200 years.). Even marine mammals can grow to great ages: the bowhead whale can live for at least 211 years.
However, only a few creatures have the equivalent or lower mortality rates the older they get, and these are known as 'biologically immortal'. Only a few organisms are like this: Sanicula (a plant), skin beetles, the Hydra (an unusual invertebrate), and the immortal jellyfish, to name a few.
What an extraordinary creature!

Until next time, keep on the wild side!

Tuesday, 2 August 2016

Incredible Invertebrates #01: the steampunk insect with gears in its legs

This is the first of my series of blog posts which will be focused on, yes, you guessed it, incredible invertebrates. While rare, magnificent, or cute animals get a lot of attention, the tiny miracles that are happening everyday amongst the little creatures, are just as remarkable. A case in my point: I challenge you to find a species of elephant or rhinoceros with gears in its legs! An impossible, crazy thing for a real animal, right? Well, not exactly . . .

Issus coleoptratus is a species of true bug in the infraorder Fulgoromorpha, more commonly known as planthoppers. These insects can be found across the world, and over 12,500 species have been discovered. In the UK, most planthoppers are rather small, and are most well-known to the public by their nymphs, which produce a frothy substance around them commonly known as 'cuckoo spit'. This foam is common on vegetation during the summer, and often I have been using my sweep net in a meadow, when I find a blob of cuckoo spit on my hand. The froghopper nymph produces this substance to deter predators, as they hide amongst the foam until they are an adults.

 An example of a particularly colourful British froghopper, Cercopis vulnerata.

 Another rather colourful species, Evacanthus interruptus

I am sure that most people who are interested in natural history, will have heard of these insects, or the cuckoo spit that they produce. What they may not know, however, is that these creatures have gears in their legs!

Which leads us back to I. coleoptratus. This species is fairly common and does not stand out as particularly special. It grows up to 7 millimetres long, and is usually a dull shade of brown or olive. It feeds on a substance found in trees called phloem, and it cannot fly. The nymphs of this species were being studied by Gregory Sutton of the University of Cambridge, and in particular he was interested in how they jumped. He noticed that when they pushed themselves off, their hind legs moved within 30 microseconds of each other, every single time. Pretty impressive coordination, but essential for an animal that relies on jumping to escape predators. After all, if the legs were out of time when they pushed off, it could send the insect spiralling off on a slant. 

 Of course, the real question is not why it needs such fine precision, but how it manages it - there wouldn't be time for the nervous system to control such things. This baffling discovery was followed by some experiments on the insects, which came to an incredible conclusion.
On the base of an insect's leg is a segment called the trochanter. In the froghopper, the trochanters of both hind legs have fine ridges (each tooth is around the fraction of the width of a hair!), and as the bases of the hindlegs touch, the ridges interlock - just like gears. As the legs pushed off, the ridges rolled against each other, keeping both limbs in time with the other.

These gears in I. coleoptratus are only present in the nymphs. Once they become adults, they shed their skin, and the ridges on their trochanters with it. So are the adults doomed to go spinning off in an uncontrolled jump every time they try and leap away from danger? Well, actually they're even better at jumping than the nymphs are! Instead, the adults probably use friction to help synchronize their legs, though this is not yet fully understood and definitely not for certain. But why don't the adults keep the neat gear system that works so well for the nymphs? Well, the thing about adult froghoppers is that they never moult, so if part of their cogs broke, they wouldn't be able to grow it back when they shed their skin, as the nymphs would do. If they lost a single tooth on the cog, then the damage would remain there, and it would always spin off to the side when it tried to escape from a predator, making it much more vulnerable than in a controlled jump. This is probably the reason why the adults don't use the same cog-like structures of the nymphs.

The gears found on I. coleoptratus are not unique, however: all planthoppers have them. In fact, people have known about these structures since the 1950s, but nobody knew what they were for. No further research was done on them, until Gregory Sutton, while studying insect movement, unwittingly stumbled upon the answer.

Now if you see some cuckoo spit in your garden, you will be able to admire the wonder of nature that lives within it: the steampunk insect with gears in its legs. The humble froghopper is truly an incredible invertebrate.

Until next time, keep on the wild side!

Monday, 1 August 2016

Wasps: amazing creatures, not a menace!

First of all, a little update on recent happenings. A few weeks ago it was my birthday, and I became 14 years old. It was quite odd, as somehow being 14 seems a lot more like being a teenager than being 13 does! I had a really good day though, and the next week, I met up with my friends, slept in a hammock in the woods, and went boating on a river! My friend, Eden, spotted a pair of grass snakes, and later I spotted a kingfisher darting away upriver.

The mystery bone that I talked about here has not yet been identified. I have asked around on Twitter, and although people have been very helpful, as to yet I have no definite answer. My thanks to those giving me advice though!

Now, onto the subject of this blog post. You may remember that I recently talked about the wasp nest which my dad and I found in our shed (see the post here). Well, the nest is still going strong, and is increasing steadily in size! It has now doubled in size since the first time I talked about it on the 23 June (the date that I write this on is the 1 August). The activity around the nest is also increasing - it is becoming slightly nerve-wracking to enter the shed with the whirlwind of wasps coming out of the nest.

 The wasp nest in June. It has now been mended by the wasps, who have also been busy with home expansion: the nest is now approaching the size of a pumpkin!

As my parents asked questions about the wasps, I realised that my knowledge of wasps is very low, so I wanted to find out some more information. Here's some questions that I had, and the answers that I have found:

 What happens to wasps in the winter?
The whole nest dies! Yes, after all the hard work during the rest of the year to build the nest, the workers all die and the nest will never be used again! The lack of food kills the wasps off, but this is completely normal, and a natural part of the insect's life cycle.
However, not all of the colony dies. The young queens live on, and will hibernate during the winter months. They do not do this is in a nest, instead they will find a sheltered place to hibernate. Many people think that a particularly cold winter is bad for wasps because it will kill the queen. This is a myth: the queen is actually perfectly safe from cold temperatures in her peaceful state of hibernation. In fact, a particularly mild winter is bad for wasps - it means that the queen awakens early, but because there is no nectar for her to eat, she dies.

What happens next to the queen?
As spring arrives, the queen will emerge from hibernation. She has 2 things on her mind: food, and making a new nest. Once she has found a suitable place to make her nest, she will begin building. She uses her mandibles to scrape up wood and chew it into a pulp, before building a new layer of her nest with it. She will lay her eggs in the nest to keep them safe, and once they emerge into grubs, she will undergo a change in behaviour. Until now she has been a nectar-feeder, a valuable pollinator to flowers. This stops once her eggs hatch. She will stop foraging altogether, instead living off the sugars which can be found in insect exoskeletons (more on that later). But what caused the queen to stop foraging? Well, the amount of work she's doing! During the early days of her nest, she is so busy that she simply has no time for feeding herself. This is because, as well as expanding the nest and collecting wood, she must also begin hunting insects. She does not eat them herself, but instead give them to her grubs, who need more protein than what can be found in nectar.
The strangest part is yet to come, however. So far the vision of an attentive mother feeding her babies has been fairly normal. But as the larvae munch away on their insect food, they convert the exoskeletons of their food into sugars, which they then feed to the queen! The mother is not only feeding her offspring, but her offspring are feeding her!
The grubs' chores don't end there, though. When the queen returns to the nest with a mouthful of wood, she will give it to the larvae, which will quickly chew it up for her, mixing it with their saliva to form the pulp used to layer onto the nest. The grubs can do this job much quicker than the queen could.

How does the nest progress after that?
The larvae pupate and become adult workers, and take over nest care duties. This gives the overworked queen a nice rest - well, almost. From now on she has a fairly easy life, simply lying in the nest and laying more eggs to increase the colony.

Are there different categories of workers?
The workers are divided into different duties:
. some wasps look after the queen, feeding her and tending to any other needs that she may have
. other wasps act as guards, protecting the nest from intruders.
. young workers have the cleaning duties, removing waste material from the nest.
. some wasps will collect water droplets, then deposit them on the outside of the nest. This is not for drinking purposes, it is actually to cool the nest.
. another caste of workers will sit outside the nest, with the unusual job of simply fanning the water. This causes it to evaporate, taking heat with it, further aiding the cooling of the nest.
. some workers will collect wood to be used in expanding the nest,
. yet another caste of workers will do the hunting: catching insects to feed to the grubs. Remember how the larvae used to feed the queen? Well, the new workers have exactly the same problem as the queen did, they're just too busy to find nectar to feed on. Instead, as before, the grubs will produce sugars to feed the workers with.
. some workers are on hand to help adult wasps emerge from their cocoons.

How do wasps reproduce?
There comes a time when the queen may chose to make special wasps. She can chose whether to lay a female egg or a male egg - the fertilized eggs form females, the unfertilized ones form males (called drones). Sometimes she will create a special female: a young queen. Exactly how she does this is unknown but it is thought that she may feed the grub a special pheromone. Because all of the queen's workers are infertile females, the drones and queens are special in that they can reproduce.
Once the drones and young queens have become adult wasps, they will emerge from the nest and produce what is known as a mating swarm. After she has mated, a young queen will not go back to the old nest, instead she will go off to a sheltered place to hibernate. And thus we are back where we started.

What happens to the old nest after this?
The queen will stop producing eggs, and she will eventually die. This has an effect on the workers, because without larvae being produced, they cannot get the sugary snack that they previously got from the grubs. Instead, they are forced to forage for themselves, being attracted to anything sugary. They will feed on fruit, nectar, and anything else they can find which is sugary. It is during this time of the year, in the autumn, that these hungry workers can sometimes be found trying to eat our food. Once the weather gets colder, and there is no nectar or fruit to feed on, the workers will die, along with the old queen.

So, there you go. If you dislike wasps, then perhaps after reading this you will at least admire them as a wonder of the natural world, and not just annoying little things which will try and eat your jam sandwhiches and sting you!

Until next time, keep on the wild side!