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SYNOPTIC DESCRIPTION OF THE SUBPHYLUM MYRIAPODA

SYNOPTIC DESCRIPTION OF THE SUBPHYLUM MYRIAPODA (LATREILLE 1802)

EUKARYA> UNIKONTA> OPISTHOKONTA> ANIMALIA> BILATERIA> PROTOSTOMATA> ECDYSOZOA> PANARTHROPODA> ARTHROPODA> MYRIAPODA
MYRIAPODA LINKS

Introduction

Hierarchical Classification

The following information came from Margulis and Schwartz (1998), Buchsbaum (1938), Barnes (1980), Barnes (1984), Brusca and Brusca (2003), Hickman (1973), Storer and Usinger (1965), and Tudge (2000).

I. SYNONYMS: myriapods, millipedes, centipedes, arthropods.

II. NUMBER: >11,500 species known.

III. PHYLUM CHARACTERISTICS:

  • A. Structure
    • Symmetry: Bilateral; presegmental acron and postsegmental telson (text with tooltip) A telson is the terminal segment of some crustaceans, certain chelicerates, and some hexapods. with 19 to >200 intervening segments, each with a pair of limbs (although the limbs may be highly modified or lost).
    • Body Cavity: True coelom (text with tooltip) A coelom is a fluid-filled cavity that lies between the outer wall and the digestive tract that is bound by a specialized epithelial tissue called peritoneum. In this condition, all organs in the coelom are connected to the body wall by mesenteries. reduced and absent in adults. Haemocoel (text with tooltip) tipso the only body cavity.
    • Body Covering: Covered by chitinous exoskeleton.
    • Support: Hardened exoskeleton.
    • Digestive System: Food tube simple. Mouth anterioventraly with mandibles (text with tooltip) Mandibles are the lower jaws of vertebrates. In arthropods mandibles are modified legs that serve as biting mouthparts. , maxillae (text with tooltip) Maxillae (maxilla, sing.) are the paired lateral jaw-like appendages on the head or cephalothorax of arthropods; the upper jaw in vertebrates. (second maxillae sometimes fused into labium) and often bears palps. Food tube of three regions: fore- (text with tooltip) The foregut (also called the stomodaeum) is the anterior portion of the gut that is lined with ectoderm. , mid- (text with tooltip) Midgut (also called mesenteron) is the mid portion of the digestive tract, lined with endodermis and derived from the archenteron. , and hindgut (text with tooltip) The hindgut is the posterior portion of the gut that is lined by ectoderm. . No caecae. 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. Millipedes have fused paired segments ( diplosegments (text with tooltip) The diplosegment is the fused double segment of millipedes. ) with two pairs of walking legs attached to each diplosegment.
    • Excretory System: Malpighian tubules (text with tooltip) Malpighian tubules are excretory organs in arthropods. They are fine tubules attached at the hind gut and bathed in the haemolymph (blood) of the haemocoel from which they remove nitrogenous waste. discharge into gut at junction of mid- and hindgut.
    • Nervous System: Circumesophagial brain and a double, ventral nerve cord with segmental ganglia (text with tooltip) A ganglion (ganglia, pl.) is a cluster of nerve cells. A brain is an enlarged ganglion. . The head capsule (fused segments at the anterior end) has simple and compound eyes (text with tooltip) A type of eye characteristic of most arthropods. It is made of many individual simple ommatidia (ommatidium, sing.), each of which is like a simple eye with a lens and light-sensitive cells. as well as antennae, sensory hairs.
    • Endocrine System:
    • Respiratory System: Tracheal (text with tooltip) Trachea (tracheae, pl.) is the windpipe of vertebrates, the air-filled tubes in most arthropods. system, usually paired spiracles (text with tooltip) Spiracles are openings on the abdominal segments of insects and body segments of myriapods through which air enters the tracheal system. It also is a small circular gill slit in some chondrichthyes. at each segment. Likely, this is convergent with the tracheal system of the hexapods.
  • B. Reproduction:
    • Reproductive System: Dioecious (text with tooltip) Dioecious organisms have separate male and female individuals. . Gonads (text with tooltip) Gonads are sex glands in animals. Ovaries produce eggs and testis produce sperm. one to many. Fertilization internal (by spermatophores (text with tooltip) A spermatophore is a gelatinous packet of sperm, which is transferred to another in the process of mating. This occurs in many invertebrates. ). Oviparous (text with tooltip) An oviparous (adj.) animal is one that releases eggs in its life cycle. They may be fertilized internally or externally. .
    • Development: Direct development.
  • C. Ecology: Mainly terrestrial.
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By Jack R. Holt and Carlos A. Iudica. Last revised: 02/03/2013
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