Most remarkable is this method of blood supply for it is exceedingly common among the invertebrates and rare among the vertebrates.
In the first place, there is the fascinating story of the origin of vertebrates from invertebrates of the sea scorpion or spider type.
Invertebrates and |Palaeozoic Period--Reign of Fishes, and afterward great | Invertebrates and Fishes.
The invertebrates of the deep sea are mostly transparent and of a blue or violet tint, while the fishes are gray or bluish above and white beneath, which renders them inconspicuous to their enemies.
Among invertebrates such animals as crayfish will acquire new habits, or rather will modify old ones.
Yet how could the first deviation from the ganglionic system of the nerves of the invertebrates to the cerebro-spinal system of the vertebrates have occurred?
We have mentioned, in the foregoing section, that the main types of the invertebrates appear somewhat contemporaneously and without any traceable intermediate form.
And hosts of the marine invertebrates have larval forms which have but little resemblance to their adult parents.
But in the higher invertebrates and vertebrates there is a sex-differentiation among the individuals, the adult males being possessed of testes only and producing sperms, the adult females possessed of ovaries only and producing ova.
FL] We have not been able to do more than make a rapid survey of the sense of sight as it seems to be developed in the invertebrates and lower animals.
But in a great number of the lower invertebrates very little or nothing is known concerning a sense of smell.
We cannot, I think, hope to know how much or how little the invertebrates feel--to what degree they are psychologically sensitive.
And this naturally suggests the question whether those sense-organs in the invertebrates which contain otoliths may not be regarded with more probability as organs for the appreciation of changes of motion than as auditory organs.
But among the invertebratesthey are not inconsiderable.
Some organs described as tactile or olfactory in the lower invertebrates are so described on a somewhat slender basis of evidence.
If nudibranchs and other marine invertebrates be protectively coloured, there must be corresponding perceptual powers in the fishes that are thus led to avoid them; for there seems to be definite avoidance, and not merely indifference.
The lower vertebrates, the invertebrates of land and sea, and the plants of field and forest take on a modern aspect, and differ little more from those of to-day than the plants and animals of different countries now differ from one another.
We must pass over the ever-changing groups of the invertebrates with the briefest notice.
In the Cambrian, Ordovician, and Silurian the invertebrates were represented in all their subkingdoms by a varied fauna.
Little needs to be said of the Tertiary invertebrates, so nearly were they like the invertebrates of the present.
Name five invertebrates that live in the water only and five that burrow in the mud or sand.
Name twenty invertebrates which you have seen and give the locality where they were found.
Name five invertebrates used as food and state where they are found.
Animals Without Backbones In general the Invertebrates are animals without a backbone; that is, they do not have an internal supporting skeleton of bone, as does the dog or cat.
There are several different groups of Invertebrates and between these groups there are greater differences of structure than there is between a horse and a hummingbird.
The Jurassic fauna is specially noteworthy on account of the character of the vertebrata, but some notice of the invertebrates must also be taken.
The most abundant vertebrate remains will be those of fishes, and of the invertebrateswe find mollusca preponderate.
Little need be said of the Pliocene fossils: the flora approaches that of present times, and the invertebrates are in most cases specifically identical with those now living.
Amongst the marine invertebrates reef-building corals and mollusca perhaps furnish the best evidence of climatic conditions.
It must be remembered, however, that the sedentary invertebratesof the bottom glow with phosphorescence.
These animals have other important peculiarities of structure (especially in the chorda and the gut) which show a striking divergence from the other invertebrates and resemblance to the vertebrates.
Only one single group of invertebrateshas a similar structure: the rare, marine tunicata, copelata, ascidia, and thalidiae.
But there is one most important fact which ought to make us hesitate before accepting the homology of the dorsal heart of the arthropod with the ventral heart of the vertebrate--The heart in all invertebrates is a systemic heart, i.
Formation of notochordal tissue in invertebratesfrom closed portions of the digestive tube.
Any attempt to discover how vertebrates arose from invertebrates must be based upon the study of Comparative Anatomy, of Palaeontology, and of Embryology.
Those invertebrates whose central nervous system is most concentrated at the cephalic end belong to the arachnid group, among which are included the various living scorpion-like animals, such as Thelyphonus, Androctonus, etc.
Among the whole of the invertebrates at present living on the earth, is there any sign of an internal cartilaginous skeleton that will give a direct clue to the origin of the primitive vertebrate skeleton?
In this part of its vascular system Ammocoetes again resembles the higher invertebrates more than the higher vertebrates.
Leydig in arthropods 'Punktsubstanz,' and known in vertebrates and in invertebratesat the present time as 'neuropil.
In the muscular group, Biedermann, who has made a special study of the physiology of striated muscle, says that among invertebrates the striated muscle of the arthropod group resembles most closely that of the vertebrate.
The object of this book is to attempt to find out from what group of invertebrates the vertebrate arose; no attempt is made to speculate upon the causes of variation by means of which evolution takes place.
In all the higher invertebrates this capillary system can hardly be said to exist; the blood is pumped from the arterial system into blood spaces or lacunae, and thus comes into immediate contact with the tissues.
While engaged in his work on theinvertebrates he found that the fossil remains of animals had not been carefully explored, so for a time he devoted himself to paleontology.
After 1840 he devoted himself to the study of invertebrates and investigated the starfish and the pentacrinites.
We shall therefore devote more attention to the birds than to the other classes of vertebrates, just as we selected the insects among the invertebrates for special consideration.
Of the invertebrates all, except the insects, are preserved in alcohol or formalin.
The Life of the Quaternary During the entire Quaternary, invertebrates and plants suffered little change in species,--so slowly are these ancient and comparatively simple organisms modified.
Notes on the Eggs of Some Laguna Beach Invertebrates P.
Wanted--Separates relating to the nervous system and sense organs of the invertebrates in exchange for reprints by a number of authors on this and other topics relating to the anatomy of invertebrate animals.
It feeds primarily upon vertebrates found in or near water; but invertebrates and eggs have also been found in the diet.
The food of cottonmouths consists mainly of small vertebrates and occasionally invertebratesthat are found near water.
An embryo or certain invertebrates in the stage when the primitive band is first developed.
Moreover, the various forms it takes in the invertebratescan always be reduced to one of the four types of segmentation described above.
What is called the "blastula" of the mammal and the real blastula of the amphioxus and many of the invertebrates are totally different embryonic structures.
But he by no means confined his attention to these, gradually taking the various groups of the invertebrates into his sphere of study.
A group of wormlike invertebrates having, along the sides of the body, branchial openings for the branchial sacs, which are formed by diverticula of the alimentary canal.
One of the artificial group of invertebrates of various kinds, which live parasitically upon the exterior of other animals; an ectozo\'94n.
The anal opening of certain invertebrates and fishes; also, the external cloacal opening of reptiles, birds, amphibians, and many fishes.
A receptacle, or pouch, connected with the oviducts of many invertebrates in which the eggs are retained until they hatch or until the embryos develop more or less.
A group of invertebrates including the Tunicata and Enteropneusta.
Any contractile vessel of invertebrates which is not of the nature of a real heart, especially one of those pertaining to the excretory system.
The term pupa is sometimes applied to other invertebrates in analogous stages of development.
A grand division of the animal kingdom, intermediate, in some respects, between the invertebrates and vertebrates, and by some writers united with the latter.
A pore by which the water tubes of various invertebratesopen externally.
In most invertebrates the years are immovable ocelli, or compound eyes made up of numerous ocelli.
The large sub-family of forms called "The Vertebrates" are distinguished from the Invertebrates by reason of the former possessing an internal bony skeleton, the most important feature of which is the vertebra or spinal column.
They are protected in a way similar to the invertebrates having shells, and yet have the additional advantage of easy movement.
It is, however, interesting to note that, with this exception, almost all the other leading groups of Invertebrates are known to have come into existence during the Cambrian period.
In many Invertebrates there is no separation of the body-cavity into thorax and abdomen, and it is only in the higher Annulosa that a distinct abdomen can be said to exist.
Phosphate of lime forms the larger proportion of the earthy matters of the bones of Vertebrate animals, and also occurs in less amount in the skeletons of certain of the Invertebrates (e.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "invertebrates" in a variety of sentences. We hope that you will now be able to make sentences using this word.
