In many Annelidsthe body is ringed, and each segment bears a pair of appendages, but these appendages are soft, and never articulated.
The morphologist would derive all the varieties of Arthropod segments from the very simple and uniform chitinous cuticle found in Annelids and many Insect-larvæ.
Not a few other animals, such as Annelids and Mollusca, exhibit the same arrangement.
Annelids from Laguna Beach This list includes specimens recently determined by Dr.
Ask the neighbouring Annelids and the fry of the rock fishes, or put it into a vase at home, and see.
In some Annelids the central nervous system remains throughout life as part of the outer epidermis, but as a general rule it becomes separated from the epidermis and embedded in the mesodermal tissues.
In Annelids the bulk of the mesoderm has at first a modified epithelial form similar to that of Arthropods, but it is formed, not from a primitive streak, but from some peculiar cells produced in cleavage, called pole-cells.
In Annelids with trochosphere larvae a certain amount of mesenchyme is formed at an earlier stage and gives rise to the muscular bands of the young larva.
Defn: One of the saclike organs from which the setæ of annelids arise.
Defn: A division ofannelids including those which construct, and habitually live in, tubes.
Defn: A genus of transparent marine annelids which swim actively at the surface of the sea.
Defn: A division of annelidsincluding the common earthworms and allied species.
Defn: Any one of numerous species of small, fresh-water, chætopod annelids of the tribe Naidina.
In annelidsthe fluid which they contain is usually red, but in some it is green, in others yellow, or whitish.
Defn: Any one of numerous species of tubicolous annelids of the genus Serpula and allied genera of the family Serpulidæ.
Defn: The act or phenomenon of spontaneously dividing transversely, as do certain species of annelids and helminths; transverse fission.
Defn: Any species of marine annelids of the genus Maldane, or family Maldanidæ.
At any rate in those regions where physical conditions render it impossible for these Annelids to have their being.
In these Annelids the attachment of the cocoon to water plants, which are liable to be entangled in the feet of shore-frequenting birds, would tend to favour migration.
Both Dohrn and Semper started out from the fact that Annelids and Vertebrates are alike segmented animals, and it was an essential part of their theory that this resemblance was due to descent from a common segmented ancestor.
Much difference of opinion reigned as to the true homologies of the brain and mouth of Annelids and Vertebrates.
The hypothetical ancestral forms (Protochordata) possessed a notochord, a ventral suctorial mouth and numerous gill-slits, and were presumably descended from the common ancestor of Annelids and Vertebrates.
Vertebrates, and comparing the lateral line of sense organs in Annelids with the lateral line in Anamnia.
The oldest and lowest tracheata are the primitive air-tube animals, or protracheata, and form the link between the olderannelids and the myriapods.
Of the three great classes of the articulates the annelidsare developed directly from the vermalia, of which both the nematoda and nemertinae approach very closely to them.
In both stems the articulation is similar in the lower and upper forms, as we find in the annelids and myriapods, the acrania and cyclostoma.
For the work of removal of this decaying matter, the carnivorous annelids and the Crustacea, mostly trilobites, were the only organisms, and it is probable that the latter did their full share.
The earliest crustacean-annelids possessed large labra or prostomia projecting backward, still retained in the Apodidae and trilobites.
It would no doubt be easy to point to vessels in existing Annelids which might be regarded as their equivalent, but to do so would be in my opinion to follow an entirely false morphological scent.
The two in Elasmobranchii communicate posteriorly by a capillary system, and in front by the arterial arches, connected like the similar vessels in Annelids with the branchiae.
A division of annelids in which the gills arise from or near the head.
Eggs like those of most sea urchins belong to the former, eggs like those of some starfish and annelids belong to the second or third type.
Lillie[71] has studied the very striking phenomenon of transitory sperm agglutination which takes place when the sperm of a sea urchin or of certain annelids is put into the supernatant sea water of eggs of the same species.
Wilson[131] has found a marked differentiation in the eggs of some annelidsand molluscs.
That the mouth of an animal can migrate seems at first impossible, but if we had time to examine the embryology of annelids and insects, it would no longer appear inconceivable or improbable.
Annelids and arthropods: The external locomotive skeleton leads to temporary rapid advance, but fails of the goal.
But the annelids were probably the first animals to develop an eye capable of forming an image of external objects.
Then the flat worms and mollusks took to a creeping mode of life, while the annelids and vertebrates still swam.
Far better means of grasping food than the horny teeth of annelidswill yet appear.
The legs are the parapodia of annelids carried to a vastly higher development.
Then the annelids settled to the bottom and crept, and all their descendants remained creeping forms.
Moreover, we have seen that the parapodia of annelids naturally point to the development of an external skeleton, for their muscles are already a part of the external body-wall and attached to the already existing horny cuticle.
Thus in the advance of annelidsto insects the muscular system increases in relative bulk, and absolutely in complexity.
It is interesting to note that a form, peripatus, still exists which stands almost midway betweenannelids and insects and has only four segments in the head.
Along the line leading from annelids to insects instinct is becoming dominant.
A genus of tubicolousannelids having a circle of plumose gills around the head.
The primitive mouth and esophagus of the embryo of annelids and arthropods.
The act or phenomenon of spontaneously dividing transversely, as do certain species of annelidsand helminths; transverse fission.
With the exception of five species of annelids (see Figure 460) brought to light by Mr. Salter in Shropshire, and Dr.
But if we exclude the Platodes and the Annelids from this stem, we find a fairly satisfactory unity of organisation in the remaining classes.
The further evolution of this rudimentary vascular system can be gathered from the class of the Annelids in which we find it at various stages of development.
Such a set of segmentally arranged lateral sense-organs is found in annelids in connection with the dorsal cirri of the ventral parapodia.
In both cases the highest products of the evolution have become markedly segmented animals, in the former, annelids and arthropods; in the latter, vertebrates.
A concentrated nervous system of this type is common to all the segmented animals from the annelids to the vertebrates, and in all cases the germ-band which indicates the first formation of the embryo is in the position of this nervous system.
The group of annelids from which the protostracan ancestor of the vertebrates arose was the highest annelidan group, viz.
We also got a few Polynae, and several otherannelids of the family Amphinomidae.
Among the Annelids was one with long glassy opalescent bristles surrounding the oral aperture, and projecting forwards to a distance of one and a half inches from the prostomium.
Nearly all Annelidsare struck with paralysis when this fluid is made to escape from its cavity by a puncture through its external walls.
Beneath the shadow of this broad shield the segment projects laterally into another tubercle, whence issue the organs of motion, which in these Annelids are of highly curious structure.
But it may be consolatory, in view of the very plebeian character of the earth-worm, to know that various of the annelids of the sea have a much more aristocratic bearing.
Ray Lankester notices that the boring of Annelids seems quite unknown; and he mentions two cases, one by a worm called Leucadore, the other by a Sabella.
One of the peculiar minute chitinous hooks found in large numbers in the tori of tubicolousannelids belonging to the Uncinata.
A division of marine chætopod annelids which are furnished with uncini, as the serpulas and sabellas.
The annelids were supposed to be the direct ancestors, not only of the crustacea and tracheata, but also of the vertebrates.
In most of the cnidaria and many of the annelids (worm-like animals) they remain unchanged throughout life.
None of the articulates, either annelids or arthropods (crustacea and tracheata), show any trace of this type of organisation.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "annelids" in a variety of sentences. We hope that you will now be able to make sentences using this word.
