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 ".

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.

Altogether, over two hundred toxins have been isolated from the limited number of amphibian species that have been investigated.

Many species have an erect woody stem which is covered with persistent dried leaves unless there have been fires, topped by a crown of long thin leaves.

Abalone have long been a valuable food source for humans in every area of the world where a species is abundant.

Prohibitions on commercial and recreational harvest of this species have been in place since 1996.

By 1987 a comprehensive survey of the phylum was completed: in all, 4516 species and 339 genera had been named.

In the recent years, several of the apicomplexan species have been selected for genome sequencing.

Polyynes, a subset of this class of natural products, have been isolated from a wide variety of plant species, cultures of higher fungi, bacteria, marine sponges, and corals.

Both species of anoa have been classified as endangered since the 1960s, and the population continues to decrease.

Around 620 species have been recognised so far, with may more undescribed.

Some birds, especially corvids and parrots, are among the most intelligent animal species ; a number of bird species have been observed manufacturing and using tools, and many social species exhibit cultural transmission of knowledge across generations.

In Thailand, many populations of one freshwater species have been wiped out by an introduced species of snail.

Chemicals extracted from a marine bryozoan species have been investigated for treatment of cancer and Alzheimer's Disease, but analyses have not been encouraging.

Amaranths are recorded as food plants for some Lepidoptera ( butterfly and moth ) species including the nutmeg moth and various case-bearer moths of the genus Coleophora: C. amaranthella, C. enchorda ( feeds exclusively on Amaranthus ), C. immortalis ( feeds exclusively on Amaranthus ), C. lineapulvella and C. versurella ( recorded on A. spinosus ).

There are also 134 species of plants classified as " weedy " or " naturalised alien species ", being those unintentionally introduced by man, or intentionally introduced as ornamentals or crop plants which have now " gone native ", including 32 new species recorded since 1995, indicating a very rapid rate of introduction.

Because of the protections provided the species on this atoll, and the isolation of the east rim of the atoll, the species is recorded in greater densities there than anywhere else in its range ( 339 crabs / ha ).

Precisely which species of felid are able to purr is a matter of debate, but the sound has been recorded in most of the smaller species, as well as the cheetah and cougar, and may also be found in the big cats.

The largest species is probably the Collared Grosbeak ( Mycerobas affinis ) at up to and, although larger lengths, to in the Pine Grosbeak ( Pinicola enucleator ), and weights, to in the Evening Grosbeak ( Coccothraustes vespertinus ), have been recorded in species which are slightly smaller on average.

The same researchers claim the species is at least somewhat nocturnal, with peak activity being reported by one source as occurring around “ two hours after dark ” and again at dawn ( although the dawn peak was recorded in the lab and could be misleading as a result ).

In a comment on the arguments of the 1830s, William Whewell coined the term uniformitarianism to describe Lyell's version of the ideas, contrasted with the catastrophism of those who supported the early 19th century concept that geological ages recorded a series of catastrophes followed by repopulation by a new range of species.

Thirty-two cetacean species have been recorded as killer whale prey, from examining either stomach contents, scarring on the prey's body, or feeding activity.

But although it has colonized a few oceanic islands, vagrant individuals are generally rare ; in the whole of Micronesia for example, the species was only recorded twice each on Guam and Saipan in the Marianas.

Altogether, a total of almost 300 species have been recorded on the Island and adjacent reserve.

Over 300 species of birds have been recorded on the island, of which over 60 percent ( including four families and 42 genera ) are endemic.

Sixteen species of vascular plants have been recorded, of which nine are indigenous.

Other very large bony fish include the Atlantic blue marlin, some specimens of which have been recorded as in excess of, the black marlin, some sturgeon species, and the giant and goliath grouper, which both can exceed in weight.

In 2004, a tooth from a red panda species never before recorded in North America was discovered at the Gray Fossil Site in Tennessee.

The shrikes are generally monogamous breeders, although polygyny has been recorded in some species.

Co-operative breeding, where younger birds help their parents raise the next generation of young, has been recorded in both species in the genera Eurocephalus and Corvinella as well as one species of Lanius.

For example, the plant species Nertera depressa was first collected in Tristan da Cunha, but has since been recorded in occurrence as far distant as New Zealand.

The frequency and size of beachings around the world, recorded over the last 1, 000 years in religious tracts and more recently in scientific surveys, have been used to estimate the population of various whale species by assuming that the proportion of the total whale population beaching in any one year is constant.