Amphipoda Sentence Examples
Their appearance in the air-breathing Arachnids does not separate those forms from the water-breathing Arachnids which are devoid of them, any more than does their appearance in certain Amphipoda separate those Crustaceans from the other members of the class.
Only in the male do the second antennae attain considerable length, with strong resemblance to what is found in some of the Amphipoda.
Many of the Amphipoda are extremely voracious.
In the Decapoda three pairs are thus modified, and in the Tanaidacea, Isopoda and Amphipoda only one.
In the other Malacostraca the heart is generally abbreviated, and even where, as in the Amphipoda, it is elongated and tubular, the ostia are restricted in number, three pairs only being usually present.Advertisement
In some Amphipoda the secretion of glands on the body and limbs is used in the construction of tubular cases in which the animals live.
In certain Copepoda and Ostracoda glands of the same type produce a phosphorescent substance, and others, in certain Amphipoda and Branchiura, are believed to have a poisonous function.
Apart from certain doubtful and possibly abnormal instances among Phyllopoda and Amphipoda, the only exceptions are the sessile Cirripedia and some parasitic Isopoda (Cymothoidae), where hermaphroditism is the rule.
A few Isopoda are known from Secondary rocks, but their systematic position is doubtful and they throw no light on the evolution of the group. The Amphipoda are not definitely known to occur till Tertiary times.
The absence of such renal caeca in Limulus and their presence in the terrestrial Arachnida is precisely on a parallel with their absence in aquatic Crustacea and their presence in the feebly branchiate Amphipoda.Advertisement
Renal excretory caeca (Malpighian tubes) are developed from the proctodaeum (not from mesenteron as in scorpion and Amphipoda).
Among the Malacostraca some Schizopoda, the Cumacea, Tanaidacea, Isopoda and Amphipoda (sometimes grouped all together as Peracarida) have a marsupium or brood-pouch formed by overlapping plates attached to the bases of some of the thoracic legs.
In the Amphipoda, the gills though arising from the inner side of the bases of the thoracic legs are probably also epipodial in nature.