Compound-eyes sentence example
The compound eyes of insects resemble so closely the similar organs in Crustaceans that there can hardly be reasonable doubt of their homology, and the primitively appendicular nature of the eyes in the latter class suggests that in the Hexapoda also they represent the appendages of an anterior (protocerebral) segment.
Watase has shown, in a very convincing way, how by deepening the pit-like set of cells beneath a simple lens the more complex ommatidia of the compound eyes of Crustacea and Hexapoda may be derived from such a condition as that presented in the lateral eyes of Limulus and Scorpio.
In the specialized ommatidia of the compound eyes of Crustacea and Hexapods the rhabdom is an important structure.'
The dorsal aspect is presented showing the prosomatic shield with paired compound eyes and the prosomatic appendages II.
Watase, " On the Morphology of the Compound Eyes of Arthropods," Studies from the Biolog.Advertisement
However different in structure Trilobites may be, they all agree in possessing a head-shield usually semi-circular in shape, which results from the fusion of apparently five segments, and bears, except in some blind forms, a pair of large reniform compound eyes like those of the king-crab (Xiphosura).
The head of a bristle-tail carries a pair of compound eyes and a pair of elongate many-jointed feelers.
The eyes of Crustacea are of two kinds, the unpaired, median or "nauplius " eye, and the paired compound eyes.
As has been already stated, the compound eyes are often set on movable peduncles.
Although typically paired, the compound eyes may occasionally coalesce in the middle line into a single organ.Advertisement
In Crustacea and Hexapoda of all grades we find compound eyes with the more complicated ommatidia described above.
But they seem to point to a community of origin of Hexapods and Crustacea in regard to the complicated ommatidia of the compound eye, and to a certain isolation of the Arachnida, which are, however, traceable, so far as the eyes are concerned, to a distant common origin with Crustacea and Hexapoda through the very simple compound eyes (monostichous, polymeniscous) of Limulus.
The first prosthomere has its appendages represented by the compound eyes and a protocerebrum, the second has the antennae for its appendages and a deutocerebral neuromere, the third has suffered suppression of its appendages (which corresponded to the second pair of antennae of Crustacea), but has a tritocerebrum and coelomic chamber.
On the other hand, the facts that the Hexapoda and the Chilopoda have triprosthomerous heads, that the Hexapoda have the same total number of somites as the nomomeristic Crustacea, and the same number of opisthomeres in the head as the more terrestrial Crustacea, together with the same adaptation of the form of important appendages in corresponding somites, and that the compound eyes of both Crustacea and Hexapoda are extremely specialized and elaborate in structure and identical in that structure, all lead to the suggestion that the Hexapoda, and with them, at no distant point, the Chilopoda, have branched off from the Crustacean main stem as specialized terrestrial lines of descent.
Watase, " On the Morphology of the Compound Eyes of Arthropods," Studies from the Biol.Advertisement
The compound eyes are very similar in the details of their structure (see Arthropoda) to those of insects (Hexapoda).