Hydration Used to Move Hairs

Biological Strategy

AskNature Team

Image: Janice Carr (photo credit) and Paul Howell (content provider) / Centers for Disease Control and Prevention /

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.

Search this Function

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.

Search this Living System

The hairs on the antennae of some male mosquitoes are elevated by hydrating protein pads adjacent to each hair socket.

Image: Janice Carr (photo credit) and Paul Howell (content provider) / Centers for Disease Control and Prevention /

At a magnification of 363x, this scanning electron micrograph (SEM) revealed some of the morphologic features of an Anopheles dirus mosquitos antennae. The antennae are composed of three basic segments: the proximal 1st segment known as the pedicel, the middle segment, or scape, and the third multi-segmented region known as the flagellum. Covered with sensorial hairs, which arent really hairs at all, but exoskeletal chitinous extensions, known as setae, they provide feedback to the mosquito as to chemical, thermal, and tactile changes in its environment.

Image: Janice Carr (photo credit) and Paul Howell (content provider) / Centers for Disease Control and Prevention /

At a moderately magnification of 293x, this scanning electron micrograph (SEM) revealed some of the morphologic features displayed on the exoskeletal surface of an Anopheles dirus mosquito. Highlighted in the field of view was the mosquitos right antennal pedicel as it attached to the head region at the clypeus. Each antenna consists of three main sections: the pedicel, which attaches the antennae to the clypeus, the scape, or mid-region between the pedicel and the last region, or flagellum, which is the composed of varying numbers of smaller segments. Also of note is the left compound eye through which the mosquito seens a composite view of its environment, much like a mosaic depiction.

Image: Janice Carr (photo credit) and Paul Howell (content provider) / Centers for Disease Control and Prevention /

At a magnification of 114x, this scanning electron micrograph (SEM) revealed some of the morphologic features displayed on the exoskeletal surface of an Anopheles gambiae mosquitos anterior head region. Included in this field of view were the two bilaterally located antennae, the proboscis, two maxillary palps, and the clypeus, to which the aforementioned structures are attached. Also note the two bilateral multifaceted compound eyes.

“At least one case of motion driven by hydration occurs in animals–the mechanism with which the males of at least one genus of mosquitoes erect the hairs on their antennae (Nijhout and Sheffield 1979). Presumably, an antenna with recumbent hairs has less drag than one with erect hairs, but only with erect hairs can a male detect the hum of a female in flight. (Females, being larger, have a lower wingbeat frequency and thus buzz at a lower pitch; a tuning fork humming such a siren song will attract males.) Adjacent to the socket of a hair is an annular pad of homogeneous (fig. 22.2); the angle of erection of the hair tracks the angle of unfolding of the pad. During unfolding and erection the pad increases in volume by 25-30 percent while the cells just beneath it decrease in size.” (Vogel 2003:444-445)

Vogel S. Comparative Biomechanics: Life’s Physical World. Princeton: Princeton University Press; 2003. 580 p.

Last Updated August 18, 2016

References

Book

Comparative Biomechanics: Life's Physical World, Second Edition

Princeton University Press | 17/06/2013 | Steven Vogel

embedly preview

AskNature