ARTHROPODA (III): General features (cont.) (Crustacea study images,
other arthropod study images;
|
Trait | Chelicerata | Trilobitomorpha | Crustacea | Uniramia |
---|---|---|---|---|
2: cephalothorax (=prosoma),
abdomen (=opisthosoma) |
3: head, thorax, abdomen (=pygidium) |
2: head, trunk (primitive) or
3: head, thorax, abdomen (derived) |
2: head, trunk (Myriapoda) or
3: head, thorax, abdomen (Insecta) | |
Body/brain region | [prosoma] | [head] | [head] | [head] |
Acron- Pr** | none | none | none | none |
Segment #1- De** | (lost) | antennae | first antennae | antennae |
Segment #2- Tr** | *+ chelicerae | * legs+ | second antennae | (lost)*** |
Segment #3 | * pedipalps/legs | legs+ | * mandible | * mandible |
Segment #4 | oviger/legs | legs+ | first maxilla | maxilla |
Segment #5 | legs | legs+ | second maxilla | labium/maxilla |
Segment #6 | legs | thoracic legs | thoracic legs | thoracic legs |
Segment #7 | legs | thoracic legs | thoracic legs | thoracic legs |
Segment #8 | abdomen limbs
(if present) |
thoracic legs | thoracic legs | thoracic legs |
in embryo | A*2 | 1*2 | 1*2 | 1*2 |
in adult: | A*2+ or 2*3 | 1*2 | 2*3 | 1*3 |
+ mouth position in
Pycnogonida only |
+ thoracic-like | *** transitory in Symphyla |
Copyright (c) 2007 by A. Richard Palmer. All rights reserved.
(revised Jan. 28, 2007)