|One pair or two
legs on each segment; adult leg no. ranges from 30 (15 pairs) to 382
(191 pairs) on Gonibregmatus plurimipes Chamberlin in Fiji (Geophilomorpha:
||Two pairs or four
legs on most segments because these are really "diplosegments" formed by
fusion of adjacent somites in the embryo; legs always on metazonite,
representing caudal of fused somites; adult leg no. ranges from 22 (11
pairs) to 750 (375 pairs) on Illacme plenipes Cook and Loomis in
San Benito Co., California (Siphonophorida: Siphonorhinidae).|
laterad and are clearly visible on sides of body; this position provides
little support and the body is carried low to substrate.
||Legs extend at
most only slightly laterad and are only partly visible on sides of body;
this position provides strong support, and the body is carried high off
|Last legs extend
backwards behind the body and are not used for locomotion.
||Last legs extend
sideways parallel to other legs.|
laterally with body.
midventrally with body; as they provide the pushing/burrowing power,
this position allows for the longest possible legs and greatest power
with least lateral extension, minimizing chance that legs may be broken
in the narrow spaces that millipedes inhabit.|
dorsoventrally flattened arthropods (except Scutigeromorpha, which is
inflexible arthropods with variable body forms that, in general, are
detritivores, though carnivory occurs occasionally in a few species;
most species in subterclass Colobognatha have long, narrow, "sucking"
mouthparts, food source and method of feeding unknown; millipedes are
ecologically important in the fragmentation of leaf litter, which
facilitates microbial decomposition and soil nutrient cycles.|
|Adapted for speed
except for representatives of the Geophilomorpha, which move slowly and
moving arthropods adapted for burrowing and 3 dfferent burrowing
mechanisms are known; some species have lost this ability and are
surface active, while others are too thin and weak to burrow and inhabit
existing cracks and crevices.|
|Adults vary in
length from 10-270+mm (1/2-10 ½ in.); largest sp. is Scolopendra
gigantea in northern South America; largest North American sp. is
S. heros, occurring from Arkansas/Missouri to Arizona and
northern Mexico (ca. 153 mm, 6 in).
||Adults vary in
length from 3-270+mm; longest sp. is Archispirostreptus gigas, in
Africa; longest North American sp. is Paeromopus paniculus in
Yosemite National Park & vic., California (160 mm, 6 ½ in.).|
("poison claws") under head with which they kill prey, and large species
can inflict a painful bite on man; they are actually modified legs and
appendages of the first segment and are not true mouthparts.
||Lack structures to
bite, pinch, or sting, and are harmless to man, although defensive
secretions burn if get into eyes; a few large species in neotropics can
squirt defensive secretions a couple of feet and have blinded chickens
|Occur in all
habitats and are prominent in deserts and arid environments.
||Occur primarily in
moist deciduous forests because most species lack a waxy cuticle as a
dessication barrier; some species occur at high elevations in "alpine"
environments and a few thrive in deserts.|
laterally (middorsally in Scutigeromorpha); in some forms they are
valvular and can be closed.
ventrally; they are never valvular and cannot be closed.|
reproductive tracts open at caudal end of body.
reproductive tracts open near anterior end of body, specifically on
segment 3; in most millipedes (infraclass Helminthomorpha) copulatory
structures in males located caudal to seg. 3, either on seg. 7 or segs.
7 & 8.|
|Males do not
possess modified legs for reproduction.
Chilognatha, males possess modified legs; in infraclass Pentazonia these
involve 1-(?)3 pairs of legs at caudal end called "telopods" that
function either to clasp female during reproduction or deposit
spermatophore directly in female openings; in infraclass Helminthomorpha
insertion is accomplished by "gonopods" on segment 7; depending upon the
order either the anterior leg pair on seg. 7, or both pairs on seg. 7,
or the posterior pair on seg. 7 and the anterior pair on seg. 8 are so
prehensors for defense; also employ aposematic coloration, luminescence,
and some species, especially scutigeromorphs, can autotomize legs; some
species produce defensive secretions.
defensive secretions from segmental defensive glands that open laterally
(middorsally in one family) [not all families have defensive glands];
secretions contain variety of noxious chemicals (quinones, terpenoid
compounds, etc.) and one order, Polydesmida, produces cyanide; also
employ defensive posture of coiling into protective spiral and in some
orders a perfect ball or sphere with head in center; also employ
aposematic coloration to warn of toxic defensive secretions and species
of genus Motyxia in southern California are bioluminescent.|