Only the embryos of Leptodora are known to hatch out in the nauplius stage.
They dug a grave for Nauplius beside the lake, and in that desert land they set up his helmsman's oar in the middle of his tomb of heaped stones.
But Nauplius was quick to ease the ship, and the wave rolled away beneath the keel, and at the stern it raised the Argo and dashed her away from the rocks.
Nauplius trod upon it, and the serpent lifted its head up and bit his foot.
Then they set sail again, and Nauplius was made the steersman of the ship.
The course was not so clear to Nauplius as it had been to Tiphys.
Tiphys knew all about the sun and winds and stars, and all about the signs by which a ship might be steered, and Nauplius had the love of Poseidon, the god of the sea.
As development proceeds, the body of the nauplius elongates, and indications of segmentation begin to appear in its posterior part.
It seems certain, therefore, that the possession of a naupliuslarva must be regarded as a very primitive character of the Crustacean stock.
In most of the Crustacea which hatch at a later stage there is, as already mentioned, more or less clear evidence of an embryonic nauplius stage.
A nauplius larva differing only in details from the typical form just described is found in the majority of the Phyllopoda, Copepoda and Cirripedia, and in a more modified form, in some Ostracoda.
B), differing widely from the nauplius in form, and possessing all the appendages of the adult.
This is well seen in the nauplius of many Cirripedia (fig.
Among the Malacostraca the nauplius is less commonly found, but it occurs in the Euphausiidae among the Schizopoda and in a few of the more primitive Decapoda (Penaeidea) (fig.
The various larval forms, especially the nauplius and zoea, were supposed to reproduce, more or less closely, the actual structure of ancestral types.
In the nauplius larva they lie rather at the sides than in front of the mouth, and their basal portion carries a hook-like masticatory process which assists the similar processes of the mandibles in seizing food.
In the Cirripedia, for example, the latest nauplius stage (fig.
Nauplius of Tetraclita porosa after the first moult.
As we have seen, it is exceptional to find a free-swimming nauplius larva among the Malacostraca, but it is the commonest larval stage in the other subclasses of Crustacea.
The later development is very unlike those which have been described above, for after a series of nauplius stages the larva passes suddenly, at a single moult, into a stage in which the body and limbs are enclosed in a bivalved shell (Fig.
B), within which no organs except the degenerating nauplius eye can be detected.
It is interesting to notice that the antennae and mandibles, which in the adult animal are so widely different that it is difficult to trace any resemblance between them, are in the nauplius almost identical in form.
But Nauplius was quick to ease the ship, and the wave rolled away beneath the keel, and at the stern it raised the Argo and dashed her away from the rocks.
There is first formed a pair of pits on the procephalic lobes, which become very deep during the Nauplius stage, and are continuous with a pair of epiblastic ridges which pass round the mouth, and join the ventral cords just described.
The three pairs of appendages of the nauplius larva (the future first and second antennae and mandibles).
The nauplius larva is of classic interest because its occurrence has enabled zoologists to determine with precision the position in the animal kingdom of a group, the Cirripedia, which was placed by the illustrious Cuvier among the Mollusca.
A, Nauplius of the Crustacean Penaeus, dorsal view.
The typical nauplius has an oval unsegmented body and three pairs of limbs, corresponding to the antennules, antennas, and mandibles of the adult.
As would be expected, the appendages of the Cirripedia are much modified, although those of the nauplius are typical.
In this theory of the origin of the Crustacea from the Trilobita, the nauplius becomes explicable and points very definitely to the ancestor.
The median or nauplius eye has not yet been found in trilobites, and if it is, as it appears to be, a specialized eye, it has probably arisen since the later Crustacea passed the trilobite stage in their phylogeny.
When so keen a student as Calman says that the nauplius must point in some way to the ancestor of the Crustacea (1909, p.
Its acceptance has forced the zoologist to look upon the nauplius as a specially adapted larva, and has caused more than one forced explanation of the protaspis of the trilobite.
One of the as yet unexplained features of the protaspis of trilobites is the absence of the "nauplius eye.
The form of the nauplius is somewhat peculiar, but it has the typical three pairs of appendages, to which are added in the later metanauplius stages the maxillae and six pairs of thoracic appendages.
The development, although modified by the early appearance of the bivalved shell within which the nauplius lies, is direct.
The higher division of Mailed Crabs (Malacostraca) have likewise originated out of the common Nauplius form.
The Nauplius at this stage gives rise to another larva form, the so-called Zoea, which is of great importance.
It was only from a knowledge of their ontogeny, and their early nauplius form (D n, Plate VIII.
Consequently, we may with assurance infer a common derivation of all those orders from a common Primaeval Crab, which was essentially like the Nauplius of the present day.
Although the different orders of the Crustacean class differ very widely from one another in the structure of their body and its appendages, yet the early Nauplius form always remains essentially the same.
The differences of the six nauplius forms are confined to quite subordinate and unessential relations in regard to size of body, and the formation of the covering of the skin.
All the six forms of nauplius entirely agree in all these essential characteristics of organization, whereas the six fully developed forms of Crustacea belonging to them, Plate XI.
The different forms of Nauplius of these six orders differ no more from one another than would six different "good species" of one genus.
And after him Erginus and Nauplius and Euphemus started up, eager to steer.
An ecdysis takes place, but the Nauplius skin is not completely thrown off, and remains as an envelope surrounding the larva during its later development.
The Nauplius is represented shortly before an ecdysis, and in addition to the proper appendages rudiments of the three following pairs are present.
If the Nauplius ancestor thus reconstructed is admitted to have existed, the next question in the phylogeny of the Crustacea concerns the relations of the various phyla to the Nauplius.
The Nauplius has a single median eye, as in the adult Cypris, and a fully developed alimentary tract.
Although in Mysis there is no free larval stage, and the development takes place in a maternal incubatory pouch, yet a stage may be detected which clearly corresponds with the Nauplius stage of Euphausia (E.
The Naupliusdiffers very markedly from that of the Copepoda, and this is still more true of the Cypris stage.
From theNauplius condition the larvae pass at a single moult into an entirely different condition known as the Cypris stage.
There are slight variations in the shape of the Nauplius in different genera, but its general form and character are very constant.
Nauplius with only three pairs of appendages, the two hinder biramous, and an unsegmented body.
The three pairs of Naupliusappendages have not altered much, but a rudimentary cutting blade has grown out from the basal joint of the mandible.
First of all, the two antennae and mandibles (the future palp) appear, inaugurating a stage often spoken of as the Nauplius stage, which is supposed to correspond with the free Nauplius stage of Penaeus and Euphausia.
The Nauplius form of the Phyllopods is marked by several definite peculiarities.
The Nauplius form of the embryo or larva of nearly all Crustacea, also points back to the worms as their ancestors, the divergence having perhaps originated, as we have suggested, in the Rotatoria.
It is evident that the Leptus fundamentally differs from the Nauplius and begins life on a higher plane.
But instead of rising to its opportunities, the sacculine Nauplius having reached a certain point turned back.
Nauplius of Tetraclita porosa after the first moult, magnified 90 diam.
A precisely similar scale is possessed by the adult Prawns, in the Zoeae of which it exists still in a jointed form, like the outer branch of the second pair of feet of the Nauplius or Peneus-Zoea.
In the case of one of these species the intermediate forms which lead from the Nauplius to the Prawn, have been discovered in a nearly continuous series.
I soon found the sight more than I could bear, and returning to the ship bade farewell to Nauplius and resumed the voyage.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "nauplius" in a variety of sentences. We hope that you will now be able to make sentences using this word.
