ARTHROPODA (III): General features (cont.) (Crustacea study images,
other arthropod study images;
|
Trait | Chelicerata | Trilobitomorpha | Crustacea | Uniramia |
---|---|---|---|---|
# of TAGMATA | 2: cephalothorax (=prosoma), abdomen (=opisthosoma) | 3: head, thorax, abdomen (=pygidium) | 2: head, trunk (primitive)
3: head, thorax, abdomen (derived) |
2: head, trunk (Myriapoda)
3: head, thorax, abdomen (Insecta) |
ANTERIOR LIMBS |
(*= mouth lies just anterior to this segment): | |||
Acron | none | none | none | none |
Segment #1 | *Ý chelicerae | antennae | first antennae | antennae |
Segment #2 | * pedipalps/legs | * legsÝ Ý | second antennae | (lost)** |
Segment #3 | legs | legsÝ Ý | * mandible | * mandible |
Segment #4 | legs | legsÝ Ý | first maxilla | maxilla |
Segment #5 | legs | legsÝ Ý | second maxilla | labium/maxilla |
Segment #6 | legs | thoracic legs | thoracic legs | thoracic legs |
Segment #7 | abdomen limbs (if present) | thoracic legs | thoracic legs | thoracic legs |
MOUTH LOCATION |
(*= location of mouth; A= acron; 1,2, etc.= segment number): | |||
in embryo | A*1 | 1*2 | 1*2 | 1*2 |
in adult: | A*1 or 1*2 | 1*2 | 2*3 | 1*3 |
. | Ý mouth position in Pycnogonida only | Ý Ý thoracic-like. | . | ** transitory in Symphyla |
Copyright (c) 2004 by A. Richard Palmer. All rights reserved.
(revised Mar. 25, 2004)