Summer\u2019s here and the time is near, for long days, sunshine (if we\u2019re lucky) and, of course, picnics in the park.\u00a0 But with picnics come the challenges of an encounter with one of the world\u2019s most efficient hunter-gatherers.\u00a0 Ants.<\/p>\n
Have you ever noticed that ants never seem to take long to find you and your picnic?\u00a0\u00a0 Not only that, but once they\u2019ve tracked you down, it\u2019s not long before a single ant becomes a huge stream of hungry and fearless food gatherers.\u00a0 Although they can be a nuisance, they deserve to be treated with respect.\u00a0 Here\u2019s a quick look at one of the most amazing family of animals on Earth.<\/p>\n
Ants have been around for a long time, always a mark of a successful group of animals.\u00a0 The oldest preserved ant is around 80 million years old, trapped, in some amber (fossilized plant sap).<\/p>\n
Latest research suggests that the ants, whose closest relatives are wasps, have been roaming the earth for at least 100 million years.\u00a0 This explains how ants all over the world are so similar; they\u2019ve been around since the time when the separate continents we see today were joined together in one single landmass.<\/p>\n
Whether you\u2019ve stumbled across an African Driver ant (the world\u2019s biggest ant \u2013 queens are up to 5cm in length) or a worker ant from a colony of Oligomyrmex bruni from Sri Lanka (the world\u2019s smallest \u2013 less than a millimetre long) you\u2019ll recognise their body shape as \u201cant-like\u201d.<\/p>\n
There are 8,800 different species of ants in the world that have been named, with more being discovered all the time.\u00a0 Estimates of how many may be waiting to be discovered vary, but most researchers seem to agree on roughly 20,000 species in total.\u00a0 Estimates vary, but at any one time, there are thought to be around 10 quintillion (that\u2019s a million-billion, or 10 with 15 zeros after it) on the planet surface.<\/p>\n
You can find ants in surprising places.\u00a0 Today, you can stumble across ants everywhere from hot deserts to the cold arctic.\u00a0 There are ants that survive in temperatures as low as \u201340C, and not one, but 14 species that make their homes on land too cold for trees to grow on.\u00a0 At the other extreme, there are some that can forage in the midday sun of the world\u2019s hottest deserts, running across the sand in temperatures that would cook an egg.\u00a0 The majority of ants, however, live in the tropics, the hot, fertile land north and south of the equator.\u00a0 In the cooler, temperate regions to the north and south of the tropics, there are 760 different species.\u00a0 In the UK we have 42.<\/p>\n
It could be strength; ants regularly carry 5 times their own body weight and can drag 25 times their weight.\u00a0 Impressive, but there are stronger insects that haven\u2019t conquered the world.<\/p>\n
It could be their stings, as they all have the ability to make acid (formic acid), which they can inject when they bite.\u00a0 Unpleasant, but many ants don\u2019t bite, choosing instead to live a more peaceful life.<\/p>\n
It certainly isn\u2019t their choice of food, as this is as varied as their choice of living conditions.\u00a0 Some ants are mainly scavengers, who pick up what they can find, others are aggressive hunters, some, even farm fungus to eat, growing it in their nests on special gardens of leaves which they collect for the purpose.<\/p>\n
The key to their success is actually organisation.<\/p>\n
Ants are part of a larger family of insects, the Hymentoptera, often referred to as the \u2018social\u2019 insects.\u00a0 This large group also includes the bees and wasps.\u00a0\u00a0 With a few exceptions, all members of this family live in colonies where every member is related to the others.\u00a0 A single queen starts the colony and then spends the rest of her life laying eggs, allowing the colony to grow.\u00a0 Because every member of the colony shares the same parents they don\u2019t compete with each other for food and space but instead work together.\u00a0 For this reason, ants and their relatives are often referred to as \u2018super-organisms\u2019 because they act together to ensure the survival of the colony just as the different parts of your and my bodies work together to keep you alive.\u00a0 Just as your body parts are specialized to do different jobs: heart for pumping blood, brain for thinking, muscles for moving things, the different members of a colony of bees, wasps or ants are specialized to do different jobs that allow the colony to function.\u00a0 Of all the social insects, the ants are the ones that show the highest degree of specialization.<\/p>\n
The different specialist members of an ant colony, are referred to as castes.\u00a0 Basically, there are workers, queens, gynes (young fertile females, potential queens of the future) and males.<\/p>\n
The Queen can live for twenty years and lays the eggs that hatch and grow to form the colony.\u00a0 With chemicals she produces (pheremones), she also, to an extent, controls the behaviour of the other colony members.<\/p>\n
Some species of ants have a single queen in their colonies whilst others have a number.\u00a0 The multi-queen species have the advantage that their colonies can survive the death of a single queen.\u00a0 One colony of Sphecomyrma freyi,\u00a0 for years thought to be the largest in the world, in Japan has 1,080,000 queens and 306,000,000 workers spread between 45 connected nests, spread over 26km of tunnels.\u00a0 Although there is still argument about this, a new, potentially larger super-colony has recently been discovered, a lot closer to home, in Europe.\u00a0 This super-colony stretches 6,000km, from northern Italy, through the south of France to the Atlantic coast.\u00a0 The ants, called Linepithema humile, are all related to each other and are invaders from Argentina.\u00a0 They were introduced to Europe around 80 years ago and have spread with incredible speed across the continent, pushing out 30 or so native species of ant.\u00a0 Because they have spread so far, so fast, their numbers have yet to rise to the levels where different colonies would be competing for the same food.\u00a0 It is thought that when their numbers rise high enough, their behaviour will change and individual colonies will start to become aggressive toward each other \u2013 as they are in their native Argentina.\u00a0 Until then, they\u2019re all on the same team, a team with several billion members.\u00a0 At the other end of the scale, nests of the British ant Leptothorax tuberointeruptus on the British coast can consist of just 50 workers and a single queen.\u00a0 These nests can fit into a space equivalent to the area between 2 one-penny pieces separated by a few grains of sand.<\/p>\n
Queens only mate once in their lives, and most of the eggs they lay will grow into sterile, female, worker ants, incapable of breeding.\u00a0 At certain times however, a queen produces eggs that will hatch into gynes, capable of becoming queens, and males.\u00a0 Although there are exceptions, gynes typically have wings, and take to the air, pursued by the males.\u00a0 The males who fly fastest get to mate with the gyne.<\/p>\n
These \u2018nuptial flights\u2019 are often synchronized, with many nests in a given area taking to the air at the same time.\u00a0 In Southern England, the common black ants, Lasius niger, all come out together, providing a feast for predatory birds and often blackening pavements with their bodies.\u00a0 After the flight, the males die; the mated female, now a queen, looks for somewhere suitable to settle down.<\/p>\n
Once she has found a suitable site, the queen loses her wings and her body re-absorbs her flight muscles.\u00a0 Her flying days are over, from now on, she\u2019ll stick to laying eggs.\u00a0 This is a priority, because until she can produce some worker ants to bring her food, she has got to survive on her internal food stores.<\/p>\n
Because of her egg-laying role, the queen is often called the \u2018most important\u2019 member of an ant colony.\u00a0 However, without workers, there would be no colony.\u00a0 The workers are the ones who, you guessed it, do all the work!\u00a0 They are also the ones that display the highest levels of specialization for their tasks.\u00a0 This is what really set the ants apart from the bees and wasps, whose workers are all very similar.<\/p>\n
The degree of variation between the different types of worker varies between species.\u00a0 Typically, there are major, medium and minor workers.\u00a0 The major workers are usually responsible for defending the colony.\u00a0 Typically, they have huge jaws, sometimes so large that they can\u2019t feed themselves and have to be fed by other workers.\u00a0 Some species of ants have major workers specialized for shifting obstacles, such as marauder ants: Pheidologeton diversius has major workers whose heads are 2.5mm across, ten times the size of the other workers.<\/p>\n
Perhaps the biggest difference in worker types is shown by the leaf-cutter ants.\u00a0 The largest are the heavily armoured and massive jawed soldiers who defend the colony (sometimes classed not as major workers but as a separate caste of ant entirely), next come the strong major workers who cut leaves from bushes and trees and carry them back to the nest.\u00a0 Within the nest there are medium workers who have blunt mouthparts adapted to chewing the leaves into pulp so they can be added to the fungus garden that grows within the nest.\u00a0 The fungus garden is tended by a class of minor workers who keep everything growing well.\u00a0 Tiny, even more adapted minor workers travel on the heads of the foraging ants to defend them against parasitic wasps.\u00a0 These wasps, unless fought away, would lay their eggs inside the forager\u2019s heads (where they hatch into maggots that would eat the ants alive from the inside out \u2013 gross).<\/p>\n
Hunting and foraging ants use their jaws, their formic acid attack, surprise and pursuit, brute force and some even have a venomous sting in their tails. \u00a0\u00a0The range of techniques and strategies is truly amazing.<\/p>\n
Perhaps the most feared ants in the world are the army ants of Africa and South America.\u00a0 They can live in huge colonies of up to 20 million individuals.\u00a0 Famously, these ants don\u2019t make permanent nests but have nomadic habits.\u00a0 When they are on the move, carrying eggs and larvae as they travel, they can form columns which are 20 metres across.\u00a0 They have a reputation for killing and consuming anything that lies in their path.\u00a0 However, although they are ferocious hunters, capable of capturing in the region of 100,000 prey items a day, they are not the \u2018lightning fast\u2019 eaters of human flesh that the movies would have us believe they are.<\/p>\n
If army ants have the simplest strategy for finding food, summarized by the rule \u2018If it\u2019s in your way eat it.\u00a0 If you can\u2019t eat it, go over it!\u2019, then the most complex feeding strategy is probably that used by the leaf-cutter ants with their fungus gardens.\u00a0 In between, there are a huge variety of hunting and foraging strategies.<\/p>\n
Aphids, insects (bugs to be precise) that tap into the sap-stream of plants are a rich source of food for many ants: for example, they are incredibly important to British black, red and wood ant species.\u00a0 The ants don\u2019t eat the bugs though, they milk them!\u00a0 As they consume sap for the sugar it contains, aphids take on a lot of water.\u00a0 This would make them explode if they didn\u2019t get rid of it, so they excrete it.\u00a0 Along with the excess water, they also lose some sugar.\u00a0 This sweet \u2018honey-dew\u2019 is a fantastic source of energy for the foraging ants who go from one aphid to the next, \u2018milking\u2019 them.\u00a0 Some ants build shelters for their aphids to protect them from predators; others actually stand guard over their aphids, defending them from attack.<\/p>\n
Foragers try to bring back excess food to the nest.\u00a0 Once there, they regurgitate it and pass it to the hungry workers, larvae and queen(s) that await them.\u00a0 This passing of food from mouth to mouth also transfers the common scent and the pheromone signals from the queen throughout the colony.<\/p>\n
Wood Ants in Britain use \u2018motorways\u2019, established, well-trodden tracks that they can find easily.\u00a0 These take the ants from the nest, to their feeding grounds.\u00a0 Once there, they can spread out to hunt\/forage.\u00a0 Once successful, or when they need to head back to the nest to get some food from another ant, they retrace their steps until they rejoin the motorway.\u00a0 Leaf-cutting ants have paths into the forest that they keep permanently free of debris so that their harvested leaves can be passed back to their nest with the minimum of effort.\u00a0 On well-worn paths like these, the sheer number of ants, visual cues from landmarks (for those ants that can see) and smell (for all ants) help them work out which way to go.\u00a0 This is great for ants that are literally surrounded by food, but what about the more opportunistic species that need to vary their searches constantly to take advantage of new or constantly changing food sources?<\/p>\n
I started this quick dip into the world of ants with a single question: how does one ant on a picnic turn into tens, even hundreds in such a short space of time?\u00a0 After zipping round the world and marvelling at the variety, complexity and success of the ant family I still haven\u2019t come up with the answer.<\/p>\n
Well, it\u2019s all due to smell, some simple logic and something called positive feedback.\u00a0 Ants recognise each other using scent, they identify food using scent, the queen sends messages using scent and, it\u2019s how they find the fastest route to food.<\/p>\n
When Common black ants (the most likely picnic invaders in the UK) forage, they start off by following a random search pattern, leaving a scent-trail as they go.\u00a0 They will keep this up until they find food, at which point they head straight back to the nest in a straight line, or come across the trail of another ant from their colony.\u00a0 They work out the direct route home by remembering the twists and turns they have made since leaving the nest.<\/p>\n
If they find another scent trail they will follow it to see where it leads.\u00a0 If it leads to nothing, they go back to random searching.\u00a0 However, if the trail leads to food, they grab some and then take the direct route home, just like the ant that found the food first.\u00a0 Although the ants that discover a trail that ends in food and join it in this way will all follow slightly different routes towards the food, they will all take the direct route home.<\/p>\n
Each ant that travels this return path, adds to the scent trail (this is the positive feedback bit).\u00a0 Providing the food doesn\u2019t run out, the scent along the direct route from nest to food keeps getting stronger and easier to follow, leading ever larger numbers of ants along it until the food supply is exhausted<\/p>\n
Simple, beautiful, Perfectly efficient – just like an ant.<\/p>\n ","protected":false},"excerpt":{"rendered":"
Summer\u2019s here and the time is near, for long days, sunshine (if we\u2019re lucky) and, of course, picnics in the park.\u00a0 But with picnics come the challenges of an encounter with one of the world\u2019s most efficient hunter-gatherers.\u00a0 Ants.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":"","jetpack_publicize_message":"","jetpack_is_tweetstorm":false},"categories":[3,4],"tags":[8,23,7],"jetpack_featured_media_url":"","jetpack_publicize_connections":[],"jetpack_shortlink":"https:\/\/wp.me\/s2VEjn-ants","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.howiewatkins.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/18"}],"collection":[{"href":"https:\/\/www.howiewatkins.co.uk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.howiewatkins.co.uk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.howiewatkins.co.uk\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.howiewatkins.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=18"}],"version-history":[{"count":3,"href":"https:\/\/www.howiewatkins.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/18\/revisions"}],"predecessor-version":[{"id":63,"href":"https:\/\/www.howiewatkins.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/18\/revisions\/63"}],"wp:attachment":[{"href":"https:\/\/www.howiewatkins.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=18"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.howiewatkins.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=18"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.howiewatkins.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=18"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}