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) | |
| prosoma] | | head] | | head] | | head] | |
Acron- Pr** | | none | | none | | none | | none |
Segment #1- De** | | (lost) | | antennae | | first antennae | | antennae |
Segment #2- Tr** | | *+ chelicerae | | * head leg** | | second antennae | | (lost)*** |
Segment #3 | | * pedipalps/legs | | head leg** | | * mandible | | * mandible |
Segment #4 | | oviger/legs | | head leg** | | first maxilla | | maxilla |
Segment #5 | | legs | thoracic leg** | | second maxilla | | labium/maxilla |
Segment #6 | | legs | thoracic leg | thoracic leg | thoracic leg |
Segment #7 | | legs | thoracic leg | thoracic leg | thoracic leg |
Segment #8 | abdomen limbs
(if present) |
thoracic leg | thoracic leg | thoracic leg |
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) 2011 by A. Richard Palmer. All rights reserved.
(revised Dec. 30, 2010)