Ingenious and innovative,

TORY and scientifi c S

too. Homes, shelters and

OVER even traps

C to catch prey built by are often well- designed and truly aesthetic – and many of them also conform to scientifi c principles.

prey! Others are artistically decorated Materials and Methods structures to woo a mate. homes When human beings fi rst began to build Y defi nition an architect is a person have many names – nests, bowers, dens, they scoured their surroundings for Bwho designs infrastructure and o en lairs, lodges, etc. materials that they could use. Stones, supervises the construction too. So, the Many animal homes are complicated mud, wood, straw, leaves...everything alliterative title of this article may have structures which are demonstrations of found use. Manufactured materials such come as a pleasant surprise to you or remarkable engineering skills; especially as bricks and cement came much later. perhaps caused your eyebrows to be when the animal does not have the So what do animals use? Animals raised. This is only to be expected because anatomical or intellectual advantage that use a variety of stuff such as mud, pebbles, the title seems to be incongruous. How we have. spider silk, fur, feathers, twigs, leaves, can animals be architects? Why would Of course, not animals need to construct structures and all animals are good Weaver ant nest (left) even if they did so; how good could these architects and not all Weaver ant dry leaves nest be? animals build homes. (below) Animal architects construct Those animals that are structures for the same reason that we celebrated architects build homes. Homes are shelters from the include corals, spiders furies of nature. A home keeps inhabitants (arachnids), insects warm and dry; snug even as hailstorms, such as termites, wasps dust storms or tempests rage outside. A and bees, crustaceans, home provides good ventilation and cool some worms, even shade when temperatures soar. It is warm molluscs, a few fi shes, when it is freezing outside. Homes are of course, a few usually safe from a acks by predators. reptiles and mammals However, not all structures are such as the great apes. homes. Some structures created by Some of the best avian animals are well-designed traps to catch architects live in India. ScienceScS iience Reporter,RReporter OCOCTOBERTOTOBEER 201620161 14 COVER STORY

SUKANYA DATTA

chain with parallel chains and reinforcing consisting of layers of diff erent algae cross-links; even multiple chains to work species. The centre has so red seaweeds. in concert and pull together the large The outer protective layer is made leaves. Finally, the leaves get folded. of scourweed (Ahnfeltia plicata). The Then the larvae on the verge of pupating protective and camoufl aging top layer is are pressed into action. Their ability to Coral weed (Corallina offi cinalis). secrete silk is used to interweave the Threespine Stickleback (Gasterosteus folded leaves with silk threads. The nests aculeatus) fi rst makes a pit in the sandy are usually pouch-like in shape and range riverbed. Then it carries sticks and aquatic in size from a single small stitched leaf to vegetation in its mouth to the pit. Then it large nests that can reach more than half a lays down a mat of fi lamentous algae, meter in length. etc. The male swims over the nest such Tent-making bats (Uroderma that a gluey cloacal secretion is brought bilobatum) construct ‘tents’ out of large, in contact with the vegetation. Once the fan-shaped leaves. They bite through the vegetation is glued together, the male midribs of large leaves and fold it into pushes through the heap, forming a roots, fl owers, fungi, lichens, mosses and an inverted-V-shape. This aff ords shelter horizontal tunnel. ferns as construction materials. They can from inclement weather. The Ninespine Stickleback (Pungitius weave leaves of plants to create a safe pungitius) secretes a drop of glue which dwelling place. Long thin blades of grass soon hardens into a thread that it grabs are suitable for interweaving and broad Using Vegetation with its mouth. Then it bores into the mass leaves are good as envelopes. That birds collect twigs and vegetation to of vegetation painstakingly accumulated Weaver Ants (Oecophylla sp.) get build their nests is well known to all. But earlier and deposits the thread there. their name from their habit of stitching that fi sh and reptiles do the same may not The thread of glue helps to consolidate together folded leaves. Worker ants pull be widely known. the structure of the nest from the inside. the edges of the leaves inwards using The Corkwing Wrasse fi sh Interestingly, the female prefers neat nests their powerful jaws. If the leaf is too far (Crenilabrus melops) constructs a large which are compact structures with li le, if away more ants join in to form a living and complex ball-shaped algal nest any, loose ends. King cobra nest (left) Reptiles are not celebrated as architects. However, the King Cobra Nest of Corkwing Wrasse fi sh (below) (Ophiophagus hannah) is unique because it is the only species of snake that builds a nest for its eggs. The female gathers loose vegetation and debris in its coil and packs the leaf li er closely to make a mound so compact that even a er torrential downpour the eggs remain dry. It usually stays on the top of the nest till the eggs hatch. Estuarine Crocodile (Crocodylus porosus) fi rst clears the chosen area and then scrapes together piles of ro ing

15 Science Reporter, OCTOBER 2016 COVER STORY vegetation and soil to form an elliptical Paper wasps are sometimes known as Umbrella Wasps because of the mound. It lays eggs in the egg-chamber upside down umbrella-shape of their nest. Mud-dauber wasps use mud where the temperature stays relatively to build their nests. The wasp rolls the mud into a ball, carries it to the stable. Heat is provided by the Sun’s rays and also by the ro ing vegetation. Cooler chosen site and applies it using its jaws. Mud is plastic when wet and can temperatures inside the egg chamber be manipulated easily. Caddisfl ies build protective cases around their tend to produce females and warmer bodies using whatever material they fi nd nearby. The most commonly temperatures produce males. used materials are underwater debris, Harvester Ants of the Western Ghats, gravel, sand, snail shells etc.. an area that receives 3-11 meters of rain Using Wood during the monsoons, build nests with chewed up plant fi bres mixed with Wasp nests range from simple structures mud walls arranged in concentric circles. salivary secretions to make a paper-like constructed by the solitary species to very This diverts water from the central nest material. complex architecture by highly social entrance. The spiral channels also slow A wasp collects dried wood fi bres species. A nest constructed by a social the water and reduce the risk of the nest from diff erent sources and uses its mouth wasp is typically made up of hexagonal being washed away. cells. Paper wasps (Polistes sp.) are parts to roll the fi bres into tiny balls. It sometimes known as Umbrella Wasps keeps these tiny spheres in its mouth as Using Underwater Debris because of the upside down umbrella- it fl ies back to the nest site. It regurgitates Sand and shells are used by aquatic shape of their nest. Wasps usually use the water it had drunk, along with other stomach contents, to paste the wood fi bres animals to make underwater homes. together into a semi-waterproof nest. All The stuff they use acts both as structural Paper wasp nests are able to resist moisture support and helps in camoufl age. nest of because of the glue-like saliva used. Caddisfl ies are moth-like insects with aquatic larvae celebrated as “underwater wasp The “paper” used by Hornets (Vespa architects” because they build protective sp. and Provespa sp.) to build their nests cases around their bodies using whatever can be peeled off in large sheets. The material they fi nd nearby. The most strength of the paper depends upon the commonly used materials are underwater length of the fi bres of which it is made. debris, gravel, sand, snail shells etc., bound together with silk secreted by the Using Mud larva. Mud-dauber wasps use mud to build their Artist Hubert Duprat provided nests. The wasp rolls the mud into a ball, captive caddisfl y larvae with 18-karat carries it to the chosen site and applies it gold fl ecks, pearls, and precious stones using its jaws. Mud is plastic when wet such as opal, turquoise, rubies, which and can be manipulated easily. It provides were incorporated into the Caddisfl y’s good compressive strength when dry. case. Caddisfl y art and jewellery is widely Po er Wasps are so called because they imitated; exhibited and sold. build miniature pot-shaped mud nests. The female Po er Wasp, Eumenes, Using Fur/Hair fi rst collects water, and then mixes it Animals also collect fur from their own with dry soil. It transfers mud pellets to bodies or that shed from other species, its jaws with the forelegs and then fl ies to add cushioning and insulation to to the chosen site. Ancistrocerus is a their homes. White-eared Po er Wasp found in India which makes (Nesoptilotis leucotis) regularly harvests exquisitely perfect, tiny pot-shaped nests. fur/ hair from livestock Kangaroos and It takes almost two hours to build its nest. even, human beings. Mud dauber nest and a nest with side entrance (centre) and mud dauber wasp at work (right)

Science Reporter, OCTOBER 2016 16 COVER STORY American robin nest American Robin fi rst makes the outer foundation by weaving long coarse grass to make a cup-shaped structure.

think that it is a visual advertisement of their presence so that birds do not blunder into the web. If so, this is an example of frugal innovation. Stabilimentum silk refl ects ultraviolet light and is a ractive to insects. Or perhaps, it has camoufl age value and the spider si ing on it hides in plain sight. Some termites use their own faeces as nest-building material. The faeces promote the growth of benefi cial bacteria that suppress potential pathogens. Acrobat Ants (Crematogaster sp.) are one of the commonest ants in Indian coff ee plantations. They use a mixture of faecal ma er and chewed up wood fragments to Overcoming Anatomical American Robin (Turdus migratorius) make their nests. The material resembles Constraints fi rst makes the outer foundation by cardboard and the ant-nest is called weaving long coarse grass to make a carton nest. The major ability that diff erentiates cup-shaped structure. Then it lines the Great Indian Hornbill (Buceros human architects from their animal inside with a layer of mud. If wet mud bicornis) almost completely seals up the counterparts is that few animals use tools. is not available, it soaks a beakful of dry nesting female inside the cavity nest using This constraint limits the kind of structures mud in water. It may soak itself in water a mixture of faeces, mud and regurgitated that animals can build. However, it must and rub its wet feathers in the dry soil to fruit: a mixture that dries like cement. be admi ed that animals make the best get mud of the desired consistency. Cave Swifl ets (Aerodramus sp.) use of their limited resources. produce sticky saliva that hardens as it For example, small birds such as Self-help is the Best Help dries; making the perfect material for its warblers use their entire bodies to create Of course, animals have an added nests. The Hummingbird (Oreotrochilus their nests. It gathers bits of grass and advantage that they can secrete the estella) uses regurgitated nectar to glue its twigs in its beak and then pushes the material they need. Most spiders secrete nests to chosen surfaces. material into the fork of a branch. It then and use silk fi bres to weave webs, rotates in such a manner that a centrally- immobilize prey, protect their eggs and Customising Material depressed area is formed. It uses its legs their young, and as a dragline to swing to Some materials such as feathers and fur and chest to push against the sides of the safety. are suitable to be used as gathered. Other nest and to compact the structure into Spiders spin diff erent types of webs. materials may need to be processed a the shape of a cup. Si ing inside the new Thus there are Orb webs, Tangle webs, li le. For example, Bagworm moths cut nest, it then uses its beak to thread bits of Funnel webs, Tubular webs, Sheet webs, the twigs into the desired size before grass to make the nest sturdier. Human etc. Some Orbweavers spin a crisscross using those to make the case within which engineers would call it “imparting band of silk through the centre of the web. they live. Bagworm cases therefore diff er structural integrity.” This is called the stabilimentum. Some in structure but not in function.

Mud-dauber Bagworm Use of twigs by Mynah to build its nest wasps make a case buzzing sound as they gather fresh mud. It is believed that the vibrations help to liquefy Bubble nest the mud.

17 Science Reporter, OCTOBER 2016 COVER STORY

AVIAN ARCHITECTURE: INTERESTING TIT-BITS 1. Some birds use leaves rich in camphor, eucalyptol, limonene, linalool, 4. Waxbills collect carnivore 6. Long-tailed Tit makes a roof dome over its nest piperotenone, myrcene and terpin-4-ol droppings and smear these which is made of spider silk cobwebs, hair, bits of etc. – compounds that inhibit the growth on, in and around the nest. moss and lichens – over 6000 pieces for a typical of bacteria, fungus, virus, and are also Chemical cues from scat reduce nest. The moss act as hooks and the spider silk insect-deterrents – to line their nests. preda on risk as it is perceived provides the loops; thus forming a natural form that the nest has already been of Velcro. Bits of lichens and moss on the outside a. Pacifi c Baza uses fresh eucalyptus robbed. provide camoufl age. The inside is insulated with leaves. thousands of feathers based on avian es mate b. Harris’s Hawk and Bald Eagle use of how many feathers are needed to regulate the Fleabane, aroma c Sedge and White 5. Cape Penduline- t builds a op mum incuba on temperature. Pine. bag-shaped nest using wool/fur. c. Blue Tit use leaves of Ligurian Yarrow The entrance can be opened and French Lavender to repel blood- or closed by the using just 7. The nest of Hammerkop is strong enough to sucking mosquitoes. one leg. An excellent piece of support the weight of an adult human. engineering is a small ridge 2. House Finch and House Sparrow in constructed just underneath urban Mexico use cigare e-stubs to the entrance for perching 8. Crested Bellbird places large, hairy caterpillars repel mites. before manipula ng the tube. on the rim of its nest and paralyses them with 3. Great-crested Flycatcher, Tu ed This nest also features a false a strategic pinch with its beak. It is not clear if Titmouse, Paradise Rifl ebird and Blue entrance that leads to a dead the caterpillars are eaten later or if these are Grosbeak drape shed snakeskin on their end. deterrents for poten al predators, or both. nests to deter predators.

Honey bees (Apis sp.) masticate Animal Architects as Ecosystem an underwater entrance. Beaver lodges the wax they produce before using it to Engineers are well-engineered with provision for construct the cells in the hive. Beavers (Castor sp.) use their large and natural heating, ventilation, and air- Mud-dauber wasps make a buzzing sharp incisor teeth to cut down trees conditioning systems. sound as they gather fresh mud. It is which they use to dam water current. believed that the vibrations help to Finally, the fl ow of the stream is blocked Man-made Structures vs Animal liquefy the mud. Tiny air bubbles escape up and a deep pond is created. In time, Architecture this becomes a productive wetland from the mud, making it more pliable. The Great Pyramid at Giza at 146.5 metres supporting a host of other species. Some This makes it easier for the wasp to gather held the record of being the tallest man- beaver dams may extend to over 300 m the mud which also dries be er helping to made structure in the world for over 3,800 across. overcome issues of improper mouldings/ years. Researchers have estimated that if cracking. Interesting, isn’t it, that an insect Dome-like Beaver lodges are the height of an average termite nest is architect should use the principles of strategically located in the middle of the compared to the size of a worker termite Thixotropy? pond and are only accessible through and the ratio scaled up to a human being 1.80 m in height, the termite construction A Beaver lodge (www.kids. britannica.com) would be like a 960-m skyscraper; over six times higher than the Great Pyramid. When proportionate sizes of human beings and termites are taken into account, the 450 m Petronas Towers are only one third the height of the average termite mound! Cathedral Termites (Nasutitermes triodiae) build mounds resembling ancient bu ressed cathedrals. The mound’s walls are porous and allow air to permeate inside. The top mound has a central chimney. This is surrounded by an intricate network of passages. Air travels through the walls into a series of small tunnels until it reaches the central chimney and rises up. When fresh air mixes with this warm air, the air cools and sinks down into the nest. This system allows effi cient ventilation ensuring that

Science Reporter, OCTOBER 2016 18 COVER STORY

ANIMAL INSPIRED LESSONS 1. Mick Pearce, an African architect and lead designer/architect for Eastgate shopping centre and offi ce building in Harare, Zimbabwe mimicked termite-ven la on systems. 2. The US army is exploring the use of honeycomb designs on the tyres of its heavy vehicles because hexagons distribute the weight more evenly and allow the tyre to support more weight. 3. The spider web is a “fl aw-tolerant op mized system” that sacrifi ces a part to save the whole. Incorpora on of such elements into buildings, especially those built in earthquake- prone areas (also aeroplanes and armoured vehicles) is being considered.

Termite hills

Hive making is a cooperative effort

When proportionate sizes of It is apt therefore that the are placed on top of the structure as a Commonwealth Scientifi c and Industrial lining. human beings and termites Research Organisation, Australia, exults, Just as human dwellings may be are taken into account, the “The construction of a large cathedral functional, luxurious or super-luxurious, mound by a termite colony is equivalent the nests of the Orangutans may also 450 m Petronas Towers are to a million, blind-folded people joining feature customised additional features only one third the height of forces to build a skyscraper covering eight such as “pillows”, “blankets”, “roofs” city blocks and towering over a mile into and even, “bunk-beds.” Pillows are made the average termite mound! the sky!” by clumping together leafy branches with the leaves in the centre. The sharp oxygen reaches the lower-most areas of Do Animals Understand edges of the twigs which may poke them the mound. Technology? are bi en off ! Sharp twigs that are not A termite species in Australia even removed are carefully oriented so that Although animals have no knowledge aligns its mounds to the Earth’s magnetic these face outwards. Large leafy branches of technology, their innate behaviour fi eld. It was not till 1970 that scientists serve as blankets. Scientists are convinced sometimes tempts us into thinking that realised that the shape presented minimal that these apes understand the natural they perhaps do understand. area to the Sun during the ho est part of fracture properties of diff erent types of the day and played a role in temperature- For example, the great apes such as wood. regulation. The unusual shape of the Chimpanzees, Gorillas and Orangutans Cliff Swallows (Petrochelidon mounds helps to keep the interior of the build nests. In general, the foundation is pyrrhonota) may fl y as far as a kilometre mound at a relatively stable temperature built by pulling together branches into a to fi nd a suitable source of mud. They use of 300C. It also helps to maintain the roughly oval shape. Then, smaller, leafy about 900–1,200 mud pellets to build their preferred high humidity. So, termites branches are bent onto the foundation. nests which they build pellet by pellet. actually regulate the microclimate inside This forms a sort of rim which increases They ensure that the underlying layer is nests. the stability of the nest. Leafy branches reasonably dry before another pellet is 19 Science Reporter, OCTOBER 2016 COVER STORY

BEST NEST: TOP CONTENDERS FROM INDIA

1) Baya Weaverbird’s nests look like snake-charmer’s fl utes. Suspended from the branches of tall trees, these are made of kno ed and woven strips of leaves or grass. This bird can e a true knot. Some mes a ‘plaited’ structure is used to hang the nest from the branch. 2) Common Tailorbird sews together broad green leaves using spider silk as thread. Using its beak as a needle, it drives the thread through the leaf. Then it grasps the thread from the other side and drives it back again in the reverse direc on. It teases out the Baya weaver bird on its nest and a hanging nest ends to form knots like the heads of rivets. The space inside is fi lled with so materials. 3) Sunbirds cra beau ful hanging purse-like nests two ends of which are a ached to suppor ng twigs. The nest is made out of fi ne plant fi bres, dry grass, petals, cobwebs, bits of lichens, crumbling pieces of bark and dried leaves. The interior is stuff ed with so material. A large leaf is usually placed on the top to serve as a roof. Tailor bird nest and stitching on the tailor bird nest

Malleefowl build huge mounds of sand with moist vegetation in the centre. Heat for incubation of the eggs is produced by microbial decomposition of the debris and also the Sun. The male bird maintains the mound temperature at 32-34 °C by using tongue/ beak as a thermometer. If the mound is too hot, it removes some vegetation so that the extra heat can escape. If the mound is too cold, it adds vegetation to improve insulation.

It appears that the bird is intuitively honeycombs. Interestingly, there are only manipulating the property of certain gels three fi gures with equal sides that can fi t that are thick under normal conditions, together on a fl at surface without leaving but which become viscous, and fl ow, gaps: equilateral triangles, squares and when shaken. This is called Thixotropy. hexagons. The Megapode birds make a compost In 36 BC, the Roman scholar Marcus heap and bury their eggs in it. The heat Terentius Varro speculated that the of ro ing vegetation hatches the eggs. hexagonal grid is the unique geometrical Australian Brushturkey (Alectura lathami) shape that divides surface area into equal and Australian Malleefowl (Leipoa cells with the smallest total perimeter. ocellata) build huge mounds of sand with Varro’s guess came to be known as the a ached to it. They use a dabbling motion moist vegetation in the centre. Heat for Honeycomb Conjecture, and not till 1999 when pu ing a new pellet into place. This incubation of the eggs is produced by did American mathematician Thomas rubs the outer margins of the older and microbial decomposition of the debris Hales prove it conclusively. It took over relatively drier pellet against the lower and also the sun. The male bird maintains two thousand years for us to prove what boundaries of the wet, new pellet. This the mound temperature at 32-34°C by honey bees have known intuitively: this ‘rubbing’ together of the wet and dry using tongue/beak as a thermometer. If shape needs the least amount of wax. mud boundaries of the two pellets results the mound is too hot, it removes some vegetation so that the extra heat can in the water contents of both pellets Dr. Sukanya Datta is a well-known author and escape. If the mound is too cold, it adds becoming similar. The consistencies of the science communicator and Senior Principal two pellets become equalised too. As soon vegetation to improve insulation. Scientist, CSIR-Central Glass & Ceramic Research as the bird stops dabbling, the junction Apis bees create tightly packed Institute (CSIR-CGCRI), 196, Raja S.C. Mullick of new and old pellets becomes stable. hexagonal structures of wax to make Road, Kolkata–700032 Science Reporter, OCTOBER 2016 20