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Text and photographs protected by Copyright © Adrian Hoskins 2007, and must not be published in part or in whole elsewhere without prior written permission from the author.
Butterfly Anatomy PAGE 2
 
PAGE 1 - HEAD
PAGE 2 - THORAX / ABDOMEN
PAGE 3 - WINGS
 
 
 
 
Abdomen
 
respiration | digestion | reproduction

The middle section of the body, the thorax, is best thought of as a muscular anchor to which the head, legs, segmented abdomen, and wings are attached.

Legs

Adult butterflies have 6 legs, although the front pair are reduced to brush-like stumps in the Nymphalidae, and absent in the males of Riodinidae. The tibia on the forelegs of Hesperiidae, Papilionidae, Pieridae and Lycaenidae are often equipped with a flexible spur through which the antennae can be drawn for cleaning.

The tibia of each leg also houses a subgenual organ, which detects and amplifies small vibrations. This way a butterfly is always extremely alert to ground vibrations caused by the approach of a potential predator, and ready to take respond by taking flight or adopting an alternative defence strategy such as when a Peacock Inachis io suddenly displays the striking ocelli on it's upperside wings.

The legs, particularly the middle pair, are covered in olfactory sensors which enable butterflies to "taste" any substrate on which they land. Females of most species tend to take a great deal of time flitting from one leaf to another, momentarily using their feet to taste the chemicals on the surface of the foliage. They are able to instantly analyse the chemicals to determine whether the plant is of the right species for egg-laying.
Leptidea sinapis, like all Pieridae species, has 6 fully functional legs
 
Euphydryas aurinia, in common with all species of Nymphalidae, has only 4 functional legs.

Wing muscles

Within the thoracic cavity of flying insects are very powerful muscles which lever on the wings. Their rapid expansion and contraction causes the wings to lift and fall at a rate of up to 1,000 beats per second in the case of bees and hoverflies, and about 200 beats per second in hawkmoths. Skippers beat their wings faster than any other butterflies, at a rate of about 20 beats per second, while Swallowtails and Pierids manage only about 5 beats per second.

Abdomen

The abdomen contains the digestive system, breathing apparatus, and sexual organs.

As can be seen in the picture below, the abdomen is multi-segmented. Each of the 10 segments is comprised of a ring of a hard material called chitin. The segments are linked by flexible tissues, allowing the abdomen to bend, a necessity for copulation and egg-laying.
The segmented abdomen can be seen in this photograph of a Grizzled Skipper Pyrgus malvae.

Respiration

On the sides of each segment are microscopic holes called spiracles, through which air enters and leaves the body. Slight rhythmic movements of the body, coordinated with the opening and closing of the spiracles, causes air to be drawn into tiny lung-like sacs, and later expelled.

Digestion

Butterflies feed exclusively on liquids, which after digestion are expelled from the anus either in liquid form, or as tiny pellets.

Reproductive organs

The genitalia ( reproductive organs ) are at the tip of the abdomen. Each species has uniquely shaped genitalia - the male "key" only fitting the correct female "lock". Because they are unique to each species, taxonomists rely heavily on microscopic examination of genitalia to determine species and classification.

Females are equipped with an ovipositor, used to release and deposit the fertilised eggs.

The females of many moths also have a scent-emitting organ located at the tip of the abdomen.

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Related subjects :
 
Taxonomy  - the classification and characteristics of butterfly families and sub-families.
Lifecycle - egg, caterpillar, chrysalis, adult butterfly, courtship, reproduction.
 
Text and photographs protected by Copyright © Adrian Hoskins 2007-2008, and must not be reproduced or published in part or in whole elsewhere in any form without written permission from Adrian Hoskins. Breach of copyright will be pursued by litigation.
 
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