Structures built by animals
Examples of animal structures include termite mounds, ant hills, wasp and beehives, burrow complexes, beaver dams, elaborate nests of birds, and webs of spiders.
They may be created by individuals or complex societies of social animals with different forms carrying out specialized roles.
These constructions may arise from complex building behaviour of animals such as in the case of night-time nests for chimpanzees,[2] from inbuilt neural responses, which feature prominently in the construction of bird songs, or triggered by hormone release as in the case of domestic sows,[3] or as emergent properties from simple instinctive responses and interactions, as exhibited by termites, or combinations of these.
Among the structures created by animals to prevent predation are those of the paper wasps, Polistes chinensis antennalis.
[8] While there are costs associated with using pulp, such as requiring time and energy to collect materials and hindering the emergence of the worker wasps from the cocoon, it does lower the risk of predation.
[8] Blue–gray gnatcatchers (Polioptila caerulea) and long-tailed tits (Aegithalos caudatus) use materials such as spider webbing, silk, and lichen, while other species such as great crested flycatchers (Myiarchus crinitus) and common waxbills (Estrilda astrild) will use animal feces and snake skins to disguise their nests.
In endothermic animals, construction of shelters, coupled with behavioural patterns, reduces the quantity and energy cost of thermoregulation, as in the case of the Arctic ground squirrels.
[11] In ectothermic animals, moderation of temperature, along with architectural modifications to absorb, trap or dissipate energy, maximises the rate of development, as in the case of the communal silk nests of the small eggar moth Eriogaster lanestris.
An interesting example is the case of silk caps which cover the pupal cells of the Oriental hornet Vespa orientalis.
[6]: 2–4 Internal architectural devices, such as walls may block convection or the construction of air flow systems may cool the nest or habitat.
[12] Traps can allow organisms to capture larger prey, provide protection from predators, or serve as an area for mating, as seen with spiders.
[13] The larva dig pits into fine-particle soil to capture their prey, which fall into the holes and are often unable to climb out.
[13] In areas with less available prey, antlions will make wider holes to increase the chance of catching an insect.
[14] These crabs may form "pillars" or "hoods" out of sand and mud to gain the attention of nearby females.
[15] During the mating season, male Bowerbirds will collect twigs and colourful objects to create structures known as "bowers", which attract the attention of females.
The nest is a flexible sac with a small, round entrance on top, suspended low in a gorse or bramble bush.
It constructs a nest of plant strips which it suspends below a large leaf using spider silk for about a 150 or so of "pop-rivets".
[17] Structures formed from plant material include beaver dams, which are constructed by foraged branches and sticks.
[22] Beavers begin to build a dam in an area where rocks and other debris slow the flow of the water.
[22] The entrance of the dam is underwater to prevent predators such as bears and wolves from entering, and the sticks at the top of the lodge are not packed tightly, which allows air into the structure.
[17] Males in some species of crab will construct structures out of mud to attract mates and avoid predators.
[24] In Chrysomelidae (leaf beetles), larvae in a few subfamilies retain their feces as shield or body armor that may be thermoregulatory, offensive, or defensive [25] In other cases, the scale wax, produced on the bodies of honey bees, is gathered and blended with saliva, to form comb wax, the building material.
These changes require significant amounts of energy and occur over long periods of time, making a caterpillar very vulnerable to predation.
[22] Some species of caterpillar, such as the silkworm (Bombyx mori) are able to spin multiple cocoons in the event that one gets destroyed.
[22] When it is time to form a cocoon, the caterpillar rips the hairs off of its body and places them around the pupating site.
[22] Recently, some researchers have argued that the structures built by animals affect the evolution of the constructor, a phenomenon known as niche construction.
