Sensory Adaptations Trivia Quiz

Answer: Hearing

Living in northern areas of South America and also on Trinidad in the Caribbean, the oilbird (Steatornis caripensis, shown in the photo) nests in colonies in caves and on ledges in gorges. They are also known to roost in trees. They like to live near their food, the fruits of the oil palm and tropical laurels.

The oilbird, known locally as the guacharo, generates its bio-sonar signal from its syrinx or vocal organ. It generally does this when navigating caves, preferring to rely on eyesight when there is sufficient natural light, combined with its sense of smell to find the fruit. It has other adaptations such as tactile whiskers, and wings which are designed for hovering and flying slowly.

Whilst there are other night-flying birds such as owls, these are carnivores or omnivores. The other fruit-eating nocturnal bird is the New Zealand-based kakapo, however this is flightless.

Answer: Rearrange its petals

This neotropical vine, Mucuna holtonii (see photo), makes itself attractive to bats using an acoustic nectar guide. Its flower contains a small concave 'mirror' which reflects most of the bat's echo-location call right back at the bat. Once the bat has sampled the nectar and loaded up on pollen, the petals rearrange themselves to make the flower less obvious and less likely to be self-pollinated by the same bat. After a few hours to a day, it changes the petals arrangement back again. As bats are nocturnal, the flowers only open in the evening or at night.

Answer: For spatial orientation

A rare adaptation amongst terrestrial animals, common shrews (seen in the image) mainly use the echo-location ability for habitat navigation, particularly in low-light conditions, rather than finding prey. Their ultrasonic calls are multi-harmonic, covering a range of frequencies at the same time. They use a bat-like scanning behaviour to pick up the echoes. As prey animals, they probably do not wish to draw attention to themselves unnecessarily so it makes sense that their sonar calls are low-powered and hence low range. The multi-harmonic nature will maximise the information available per pulse.

For hunting, they use a combination of smell, touch (using sensitive whiskers under active muscle control to sense vibration), acute hearing and vision (which, although poor, allows them to perceive light and movement).

Answer: Sound modification

All toothed whales have a melon, an organ in their foreheads. It consists of adipose tissue and acts as a lens for sound waves. As such it is used in communication and to help with echo-location of prey. The composition of the melon varies with the waxier inner parts slowing sound more than the outer parts.

The beluga whale (shown in the photo) is unique amongst toothed whales in being able to vary the shape of the melon at will. This leads to another apparent use, namely for visual communication between whales. Many mammals use facial expressions to show emotion and intent. With thick rubbery skin, belugas cannot easily express themselves in this way. Their ability to change the shape of the melon results in visual changes. It mostly occurs when the whales interact, however is not clear whether this is a reflex or intentional.

Answer: For its droppings

The relationship is in fact mutualistic. It has a structure which strongly reflects this bat's particularly high vocalisation frequencies, making it easier to find in dense jungle. The bat gets a pleasant roosting site inside the pitcher, resulting in a better body condition and fewer parasites compared to those roosting on any nearby fanged pitcher plant (Nepenthes bicalcarata). In exchange, the plant gets bat droppings, supplying perhaps a third of its nitrogen requirements.

The plant has a modified longer pitcher design to accommodate the bat, reduced fluid levels and has less in the way of insect attractants, namely no UV patterns or strong scents and less nectar production. It will still trap insects. In contrast, the fanged pitcher plant has developed to support a mutualist relationship with the ant species Camponotus schmitzl. The image shows the related Nepenthes rafflesiana.

Answer: Magnetic field detection

Other than the Guiana dolphin, monotremes such as the platypus are the only mammals known to have the electroreception sense. This is the ability to detect magnetic fields generated by living organisms. Something like 40,000 such sensors are embedded in the skin on the top and bottom of its bill, arranged in rows along its head-tail axis. Freshwater shrimp and other small aquatic animals generate a magnetic field when contracting muscles and these can be detected by the platypus from 15 - 20 cm (6 - 8 in) away.

It also has mechano-receptors which detect mechanical pressure or distortion, also on its bill. There are three types which detect pressure, rapid movement and vibration respectively. When the platypus hunts underwater, it closes its eyes, ears and nostrils. The information from both these receptor types however allows it to hunt effectively for its food.

Answer: Infra-red sensors

Infra-red receptors on the bat's nose allows the bat to identify blood vessels close to the surface of the skin on its prey. The three vampire bat species are the only mammals to rely exclusively on blood for their food. In drinking blood, their organs have had to evolve to cope with a large amounts of liquid, iron and excess protein. They also have developed a high level of resistance to certain blood-borne diseases.

Other adaptions include being able to recognise the breathing pattern of the sleeping animals and having the ability to walk, which most bats don't do well. The more powerful forelimbs (attached to the wings), rather than the hindlimbs, provide the bat with a bounding gait. The photo shows a museum display of a feeding bat.

Answer: Pheromones

In the case of hornets, there are several potential warning mechanisms involved. The non-visual warning comes in the form of pheromones given off by the hornets and picked up by the antenna on bees. The shape of the insect and its rapid flight pattern are also visual cues. Guard bees at the hive will scan the area and give a distinctive 'I see you' signal to the hornet to indicate it has been spotted as well as to warn other bees. They may also hiss aggressively.

Bees may drop to the ground to avoid aerial attack as a result. They may buzz loudly and sting the hornet to deter it. Bee balling is another tactic, forming a close mini-swarm around the hornet to overwhelm it both by the heat generated and through stinging. The image shows a honey bee.

Answer: Gravity

In addition to having the sense of touch, jellyfish have the ability to sense gravity, light, water movement and chemicals. It is gravity sensing that allows it to orient itself relative to the vertical axis, which is essential for maintaining balance and for navigation. Gravity is sensed by statocysts at the bottom of the bell rim of the jellyfish.

These sac-type organs are lined with sensor hair-like projections called setae which cushion a calcareous body called a statolith. When the jellyfish moves, the statolith will shift, stimulating some of the setae which is connected to the nervous system and allows it to orientate itself in the water.

The image shows a lion's mane jellyfish (Cyanea capillata), one of the largest jellyfish.

Answer: Mantis shrimp

Possessing one of the most complex vision systems known, the mantis shrimp has between 12 and 16 types of photoreceptors, compared to three for humans. Staring at an object is a typical animal behaviour however the mantis rarely does this, instead its stalk-mounted eyes explore its environment with pitch, yaw and torsional rotations with each eye moving independently. It can convert circular polarisation into linear polarisation, the better to maximise the contrast of its object of interest against the background.

The result is enhanced vision, navigation assistance, predator avoidance and improving hunting efficiency. Parts of its body can reflect circularly polarised light and this is used for communication purposes between members of the same species, such as mating rituals and territorial displays.