The name thyroid-stimulating hormone ( TSH ) has been given to a substance found in the anterior pituitary gland of all species of animal so tested for its presence.

With their often complex reproductive needs and permeable skins, amphibians are often ecological indicators and in recent decades there has been a dramatic decline in amphibian populations of many species around the globe.

A caecilian's skin has a large number of transverse folds and in some species contains tiny embedded dermal scales.

The development of the young of Ichthyophis glutinosus, a species from Sri Lanka, has been much studied.

A number of causes are believed to be involved, including habitat destruction and modification, over-exploitation, pollution, introduced species, climate change, endocrine-disrupting pollutants, destruction of the ozone layer ( ultraviolet radiation has shown to be especially damaging to the skin, eyes, and eggs of amphibians ), and diseases like chytridiomycosis.

By its inclusion the order has grown enormously in number of species.

The group has more than 23, 000 currently accepted species, spread across 1620 genera and 12 subfamilies.

Each abalone species has a typical number of holes in the selenizone which remain open.

Although the family ( Amaranthaceae ) is distinctive, the genus has few distinguishing characters among the 70 species included.

The species Amaranthus palmeri ( Palmer amaranth ) causes the greatest reduction in soybean yields and has the potential to reduce yields by 17-68 % in field experiments.

It has the capacity to get to large heights and can outcompete native plant species around it.

Ailanthus are capable of forming thick blankets of roots and heavy shade to the extent that native species are prevented from being able to reclaim an area that has been logged or deforested, as well as areas that have been heavily developed.

Widespread usage of antibacterial drugs in hospitals has also been associated with increases in bacterial strains and species that no longer respond to treatment with the most common antibacterials.

Although there were low levels of preexisting antibiotic-resistant bacteria before the widespread use of antibiotics, evolutionary pressure from their use has played a role in the development of muiltidrug resistance varieties and the spread of resistance between bacterial species.

Lastly, abiotic stress has enabled species to grow, develop, and evolve, furthering natural selection as it picks out the weakest of a group of organisms.

It has been observed through a variety of environments that as the level of abiotic stress increases, the number of species decreases.

Australia has several indigenous plants which are popular among modern ayahuasqueros there, such as various DMT-rich species of Acacia.

Moreover they argued that some species have been created for the purpose of being sacrificed and eaten by humans, that it is normal for animals to kill and eat other animals, that agriculture, too, inevitably leads to the death of many animals, that plants are living beings as well and must still be destroyed, that we unintentionally and unknowingly destroy life forms all the time, and that a hunted animal has a fair chance to survive by killing the hunter.

Acid rain has eliminated insect life and some fish species, including the brook trout in some lakes, streams, and creeks in geographically sensitive areas, such as the Adirondack Mountains of the United States.

It has not been definitively established whether the existence of these brainless species indicates that the earliest bilaterians lacked a brain, or whether their ancestors evolved in a way that led to the disappearance of a previously existing brain structure.

No modern species should be described as more " primitive " than others, strictly speaking, since each has an equally long evolutionary history — but the brains of modern hagfishes, lampreys, sharks, amphibians, reptiles, and mammals show a gradient of size and complexity that roughly follows the evolutionary sequence.

The relationship between brain size, body size and other variables has been studied across a wide range of vertebrate species.

The brain of a shark shows the basic components in a straightforward way, but in teleost fishes ( the great majority of existing fish species ), the forebrain has become " everted ", like a sock turned inside out.

* Bisexual species, in biology, one that has members of two different distinct sexes ( e. g. humans ), opposed to unisexual ( only one sex present, always females )

As a result of its relief and geographic situation, the Ubaye Valley has an " abundance of plant and animal species ".

They've got a big vulture from Tanganika at the zoo here, with a wife for him, too, very rare birds, both of them, the only Vulturidae of their species outside Africa.

Oliver, in his summary of the habits of the snakes of the United States, could supply data on the maturing period for only three species in addition to the rattlers, which I shall consider separately.

A number of fossil cryptobranchids have been found but there are only three living species, the Chinese giant salamander ( Andrias davidianus ), the Japanese giant salamander ( Andrias japonicus ) and the hellbender ( Cryptobranchus alleganiensis ) from North America.

It is the only living species of the order Tubulidentata, although other prehistoric species and genera of Tubulidentata are known.

The aardwolf is the only surviving species in the mammalian subfamily Protelinae.

In 2008, it was discovered that the inactivation of only two genes in one species of annual plant leads to the conversion into a perennial plant.

Blandfordia is the only genus in the family Blandfordiaceae, with four species distributed in eastern Australia.

Lanaria lanata is the only species in the family Lanariaceae and is found in southern South Africa.

The two species of Doryanthes, the only genus of the family, are huge rosette-forming herbs that are a conspicuous element of the flora in the vicinity of Sydney, Australia, being hard not to notice when in flower.

The family consists of a single genus Xeronema with two species, one found only on the Poor Knights islands in New Zealand and the other in New Caledonia.

The rest of the families together contain only about five hundred species.

Although the name actually applies to a group of snakes, it is often used to refer only to one species in particular, the common or green anaconda, Eunectes murinus, which is one of the largest snakes in the world.

However, this name is used to refer to the brown vine snake, Ahaetulla pulverulenta, a slender, arboreal species that grows to five feet ( 152 cm ) at most and feeds only on small vertebrates.

In terms of numbers of species, Asteraceae is rivaled only by Orchidaceae.

The black caiman and American Alligator are the only members of the alligator family that pose the same danger to humans as the larger species of the crocodile family.

Formerly, Sauer ( 1955 ) classified the genus into two subgenera, differentiating only between monoecious and dioecious species: Acnida ( L .) Aellen ex K. R.

*: Conoid present only in the ookinete of some species

Motile species will be able to migrate, albeit slowly, throughout the gel and infiltration rates can then be visualized, whereas non-motile species will show growth only along the now-empty path introduced by the invasive initial sample deposition.

and reiterates in no uncertain terms: " Nothing, then, which is not a species of a genus will have an essence – only species will have it ...."

All living species of birds have wings — the now extinct flightless moa of New Zealand being the only exception.

In 1709 he became professor of botany and medicine, and in that capacity he did good service, not only to his own university, but also to botanical science, by his improvements and additions to the botanic garden of Leiden, and by the publication of numerous works descriptive of new species of plants.