DIVERSITY OF LIFE

SYNOPTIC DESCRIPTION OF THE SUBPHYLUM HEXAPODA (LATREILLE 1825)

EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>BILATERIA>PROTOSTOMATA>ECDYSOZOA>PANARTHROPODA>ARTHROPODA>HEXAPODA

The following information came from Margulis and Schwartz (1998), Buchsbaum (1938), Barnes (1980), Barnes (1984), Ruppert and Barnes (1991), Brusca and Brusca (2003), Hickman (1973), Storer and Usinger (1965), and Tudge (2000).  
I. SYNONYMS: insects, bugs, arthropods.  
II. NUMBER: >1,000,000 species known.  

III. PHYLUM CHARACTERISTICS:

A. Structure

Symmetry: Bilateral with head (5 fused segments with acron and oral region with mouthparts formed by modifies legs), thorax (3 segments, each with a walking leg; most adult insects with 2 pairs of wings), and abdomen (11 segments with considerable fusion in some groups) without walking legs.

Body Cavity: True coelom reduced and absent in adults. Haemocoel the only body cavity.

Body Covering: Covered by chitinous exoskeleton.

Support: Hardened exoskeleton.

Digestive System: Food tube simple. Mouth at anterioventral end bordered by upper lip (of epistome and labrum) and lower lip (of maxillae or labium), and has mandibles. Hypopharynx. Food tube of three regions: fore-, mid-, and hindgut. Anus terminal.

Circulatory System: Open. Haemocoel of blood sinuses with a dorsal heart. No respiratory pigments in the plasma .

Locomotion: Each segment bears one pair of unbranched, jointed legs. Lost or highly modified in some.  When present, the first leg segment is the coxa (coxae)

Excretory System: Malpighian tubules (when present) discharge into gut at junction of mid and hind- gut.

Nervous System: Circumesophagial brain and a double, ventral nerve cord with segmental ganglia. The head capsule (fused segments at the anterior end) have simple and compound eyes as well as antennae, sensory hairs.

Endocrine System: Complex, with hormonal control of sexual reproduction, development, growth, and communication.

Respiratory System: Tracheal system, usually paired spiracles at each segment.

B. Reproduction:

Reproductive System: Dioecious. Gonads one to many. Fertilization internal (by spermatophores). Oviparous.

Development: Development may include larval form that is markedly different from adult.

C. Ecology: Mainly terrestrial, a few have returned to water.

 

LITERATURE CITED

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By Jack R. Holt and Carlos A. Iudica.  Last revised: 02/03/2013