Proboscis Unwinds

Biological Strategy

AskNature Team

Modify Size/Shape/Mass/Volume

Many living systems alter their physical properties, such as size, shape, mass, or volume. These modifications occur in response to the living system’s needs and/or changing environmental conditions. For example, they may do this to move more efficiently, escape predators, recover from damage, or for many other reasons. These modifications require appropriate response rates and levels. Modifying any of these properties requires materials to enable such changes, cues to make the changes, and mechanisms to control them. An example is the porcupine fish, which protects itself from predators by taking sips of water or air to inflate its body and to erect spines embedded in its skin.

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Modify Position

Many resources that living systems require for survival and reproduction constantly change in quantity, quality, and location. The same is true of the threats that face living systems. As a result, living systems have strategies to maintain access to shifting resources and to avoid changing threats by adjusting their location or orientation. Some living systems modify their position by moving from one location to another. For those that can’t change location, such as trees, they modify position by shifting in place. An example of an organism that does both is the chameleon. This creature can move from place to place to find food or escape predators. But it also can stay in one place and rotate its eyes to provide a 360-degree view so that it can hunt without frightening its prey.

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Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

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The proboscis of the butterfly unwinds from a tightly coiled position via muscular contraction and a hydraulic, step-wise mechanism.

During rest, the tube-like feeding structure of the butterfly (i.e., the proboscis, equated to a "tongue") remains coiled tightly against the head. However, when the butterfly moves to feed upon the nectar of a flower or something akin, the proboscis unfurls to extend downward into the flower’s center. The uncoiling is initiated in the muscle closest to the head, the basal galeal muscle, which lifts the coils slightly to "unlock" it from its tightly held position. The coil begins to unwind via the contraction of other muscles throughout the proboscis, known as stipes muscles. This contraction places pressure on various areas throughout the feeding tube by compressing the stipial tube. This creates a step-wise reaction that further unfurls the tube through pressurized increases in the stipes’ valve-like structures.