Category Insects

The brain is not only the most complex organ of the body but also one of the most complex things we have yet discovered in the universe. Understanding the human brain and how we think is one of the greatest challenges confronting us.

As we continue to study this wonderful organ, we are taking baby steps towards our ultimate goal. An international team of researchers led by Johns Hopkins University and the University of Cambridge recently produced the most detailed diagram of the brain of a larval fruit fly, tracing every neural network in it. The results were published in the journal Science early in March and serves as an archetypal scientific model with brains comparable to humans.

Creating connectomes

The idea of mapping a brain began as early as the 1970s when researchers conducted a 14-year study on roundworms. It resulted in a partial map and also a Nobel Prize. Partial connectomes (map of neural connections in the brain) of several systems, including flies mice, and even humans have since been developed, but these reconstructions usually represent only a tiny fraction of the brain. Comprehensive connectomes have been generated for small species such as roundworms and larval sea squirt.

In this research, the team produced the connectome of a baby fruit fly,’ Drosophila melanogaster larva’. With 3,016 neurons and 5,48,000 connections between them, this is the most expansive map of an entire insect brain ever completed.

Laborious process

Mapping brains is not only difficult, but also extremely time-consuming, despite the latest technology at the disposal of these researchers. To build a complete cellular-level map of the brain, the brain first needs to be sliced into thousands of tissue samples, which are imaged with electron microscopes, before- reconstructing the pieces, neuron by neuron, to create the portrait of the brain.

While the imaging alone took the team nearly a day per neuron (meaning around 3,000 days were spent on the task), the overall work took the University of Cambridge and Johns Hopkins 12 years. The team chose fruit fly larva as the species, for an insect shares a lot of its fundamental biology with humans.

The methods developed by this team for the mapping are applicable to any brain connection project. They are going to make the code used available to whoever attempts to map an even larger animal brain.

Despite the challenges involved, scientists are expected to take on the brain of the mouse, maybe even in the next decade. But as British zoologist and author of ‘The Idea of the Brain’ sums up in his book, knowing where things happen doesn’t necessarily translate to knowing how it happens, and our understanding of how still has a long way to go.

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You may have seen a snail on a plant or near a river. You are likely to have seen a slug in your backyard. Irrespective of where you find them or how large or small they are, snails and slugs have something spectacular in common – moving – ever so slowly. Why is that so? Come, let’s find out.

Snails and their relative slugs (without shells) are molluscs, and it is said that there are 2,40,000 of these species across the world, including in oceans. And they all move slowly. Here’s something to give you an idea of how slow they really are – in a snail race, the fastest on record sped at nearly .09 km per hour!

Apparently, there are at least three reasons for their slowness: “how they move, what they eat and what eats them”. These molluscs do not have feet like humans do. They have “a band of muscle that runs along the underside of their body and is covered in sticky mucus”. When these muscles contract, they send small waves across the creature’s body. “These waves compress the mucus on the bottom of the foot into a slippery liquid”, helping the snail or slug glide or climb. It’s an unusual way of moving, and takes time. Plus, like predators, they don’t have to run after their food. Here’s what they eat-“most slugs and snails eat plants, decaying matter or marine animals, like sponges”, which stay in one place. So snails and slugs don’t really have to hurry, worrying if their food will escape. And, they certainly don’t have to hurry to escape predators themselves. While snails are usually protected by their shells, slugs escape the attention of other creatures due to the colour of their body – greys and browns that help them “blend in well with their surroundings”. Further, land “slugs are covered with a sticky mucus”, which is “so gooey that it can gum up the mouths of predators and make it hard to chew”. Last heard, the slime is not very tasty and certainly not worth the effort just to end up with a gummed up mouth! As for sea slugs, they come in bright colours, bearing “nasty-tasting poisons”, which predators are aware enough to keep off.

Slow they could be, but snails and slugs contribute immensely to the health of their ecosystems. They feed on seeds and young plants, keeping the growth of certain plant species in check. “By eating decaying matter, they help recycle nutrients that growing plants can use. And despite their best efforts, snails and slugs do often become food for other animals.”

So, the next time you see a snail or a slug ambling by, you know what the best thing to do is – just let them be!

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Insects are small animals with no bones. An insect’s body is protected by a hard outer covering called an exoskeleton. The body has three segments: head, thorax and abdomen. The head has eyes – which can have six to 30,000 lenses – and a pair of antennae to feel, taste and smell things. The thorax has wings and legs. The abdomen includes systems for digesting food.

The insects have proved to be the most successful arthropods. There are far more species in the class Insecta than in any other group of animals. These amazingly diverse animals have conquered all the environments on earth except for the frozen polar environments at the highest altitudes and in the immediate vicinity of active volcanoes.

Insects are the only invertebrates (animals without backbones) with wings. Much of their success results from their ability to fly and colonise new habitats. The study of insects is called entomology and entomologists are scientists who study insects.

Insects play a very important role in the web of life, in every environment. Some of their jobs include pollinating flowering plants, being a source of food for insectivorous animals and assisting in the decomposition of plants and animals.

Insect classification

Modern insect classification divides the Insecta into 29 orders, many of which have common names. Some of the more common orders are:

Mantodea – praying mantids
Blattodea – cockroaches
Isoptera – termites
Siphonaptera – fleas
Odonata – dragonflies and damselflies
Dermaptera – earwigs
Diptera – flies
Lepidoptera – butterflies and moths
Orthoptera – grasshoppers, katydids, crickets
Coleoptera – beetles
Hymenoptera – wasps, bees, ants, sawflies

Insect features

The insect body is divided into three main parts, the head, thorax and abdomen.
Insects have no internal skeleton, instead they are covered in an external shell (exoskeleton) that protects their soft internal organs.
No insect has more than three pairs of legs, except for some immature forms such as caterpillars that have prolegs. These are appendages that serve the purpose of legs.
The typical insect mouth has a pair of lower jaws (maxillae) and upper jaws (mandibles) which are designed to bite. There are many variations to this structure, as many moths and butterflies have tubular sucking mouthparts, many bugs and other blood-sucking insects have sucking stabbing mouthparts and some adult insects simply don’t have functional mouthparts.
Insects have one pair of antennae located on the head
Most insects have one or two pairs of wings although some insects such as lice, fleas, bristletails and silverfish are completely wingless.

Credit : Australian.museum

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Have you heard of Nature’s eating machines? They are nothing but caterpillars. What are they and why do they eat so much? Come, let’s find out

You may have heard your mother give a small shriek when she is shelling peas and flinging away the offending pod. The culprit is a tiny green worm-like creature with miniature bristles – a caterpillar – the larva of a butterfly or moth!

Caterpillars are the animal kingdom’s most voracious eaters. They range in size from 1 mm to 75 mm. They grow phenomenally, moulting or shedding their skin several times before they spin a cocoon around themselves in the last stage. The tobacco hornworm, for instance, will increase its weight by ten thousand times in less than 20 days!

Hairy horrors

The name derives from the Latin term for hairy cat. That’s because most caterpillars are covered with spiky bristles, fine hairs or spines that are usually connected to venom glands. The secretion from the glands situated at the base of the spines can cause intense irritation and burning. The hairs can also detach and lodge in the skin.

A species of American moth caterpillar carries a sting which can cause temporary paralysis. The Brazilian flannel moth caterpillars sting is so painful, it has been christened ‘bizos de fuero’ or ‘the fire-beast!

The caterpillar of the lasiocampid moth has spiny hairs hidden beneath the folds of skin on its back. When threatened by danger, it arches its back porcupine-like and attacks the predator with its sharp quill-like hairs.

More defences

Besides hair and venom, caterpillars have evolved a variety of tactics to deter predators.

Plants have toxins to defend themselves against herbivores. Some caterpillars have managed to get around this. The caterpillars of the monarch butterfly feed only on the poisonous leaves of the milkweed plant. Not only do they remain unaffected, they are able to store the poison in their bodies unchanged! Even as pretty orange-and-black butterflies, they make a nasty mouthful and predators avoid eating them. Some caterpillars vomit acidic digestive juices on their attackers and some produce bad smells from glands which they can extrude.

A few caterpillars wiggle long, whip-like organs attached to the ends of their bodies to frighten away flies or spin a line of silk and drop off from branches when disturbed. Many species thrash about violently when disturbed to scare away predators. One species called amorpha juglandis lets out a high-pitched whistle that scares away birds.

Clever camouflage

To escape detection, caterpillars can take on the appearance of bird droppings, leaves or twigs. Some lunch in peace within a woven silk gallery, or roll up inside leaves, or mine into the leaf surface.

Do or Diet

A majority of caterpillars feed solely on plants, but there are others that feed on decaying animal matter such as wool and the hooves and horns of dead ungulates. Predatory caterpillars eat the eggs of other insects, aphids, scale insects, or ant larvae or even caterpillars of other species. A few are parasitic on cicadas and leaf hoppers. Hawaiian caterpillars use silk traps to capture snails.

Farmers’ Pe(s)ts

Caterpillars are extremely destructive and can chomp their way through fruits, vegetables and other food crops, mainly feasting on the leaves. However, there are some species of moth caterpillars that are cultivated by man for their ability to spin lustrous silk.

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A study published in the European Journal of Clinical Nutrition shows that “insects contain values of between 9.96 and 35.2 grams of protein per 100 grams, compared with 16.8-20.6 grams for meat”. However, protein density does vary widely depending on which kinds of bugs are being consumed. With over 2,100 types of edible insects to choose from, the options are endless. Crickets, certain ant species, and mealworms are the rising stars of the bug protein movement, due mostly to their calorie and protein density.

Eating insects is a great alternative for those who are concerned with decreasing their environmental footprint. On average, the resources it takes to raise and produce bugs is significantly less than animal-based meat. According to the Food and Agriculture Organization, “crickets need six times less feed than cattle, four times less than sheep, and twice less than pigs and broiler chickens to produce the same amount of protein”. They also produce significantly less greenhouse gasses than animals and it takes less land to raise them.

As the human population increases and as we continue to observe the impacts of climate change, swapping your beef burger for a cricket-based burger might be one more way individuals can contribute to a more sustainable planet.

Credit : Runtastic 

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Spinochordodes tellinii is a parasitic nematomorph hairworm whose larvae develop in grasshoppers and crickets. This parasite is able to influence its host’s behavior: once the parasite is grown, it causes its grasshopper host to jump into water, where the grasshopper will likely drown. The parasite then leaves its host; the adult worm lives and reproduces in water. S. tellinii does not influence its host to actively seek water over large distances, but only when it is already close to water.

The microscopic larvae are ingested by their insect hosts and develop inside them into worms that can be three to four times longer than the host.

The precise molecular mechanism underlying the modification of the host’s behaviour is not yet known. A study in 2005 indicated that grasshoppers which contain the parasite express, or create, different proteins in their brains compared to uninfected grasshoppers. Some of these proteins have been linked to neurotransmitter activity, others to geotactic activity, or the body’s response to changes in gravity. Furthermore, it appears that the parasite produces proteins from the Wnt family that act directly on the development of the central nervous system and are similar to proteins known from other insects, suggesting an instance of molecular mimicry.

Credit : Wikipedia 

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