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The narwhal was scientifically described by Carl Linnaeus in his 1758 publication Systema Naturae. [5] The word "narwhal" comes from the Old Norse nárhval, meaning 'corpse-whale', which possibly refers to the animal's grey, mottled skin and its habit of remaining motionless when at the water's surface, a behaviour known as "logging" that usually happens in the summer.
Viburnum lesquereuxii leaf with insect damage; Dakota Sandstone (Cretaceous) of Ellsworth County, Kansas. Scale bar is 10 mm. Knowledge of herbivory in geological time comes from three sources: fossilized plants, which may preserve evidence of defense (such as spines) or herbivory-related damage; the observation of plant debris in fossilised animal feces; and the structure of herbivore mouthparts.
Galls may also provide the herbivore protection from predators. [29] Some herbivores use feeding behaviors that are capable of disarming the defenses of their host plants. One such plant defensive strategy is the use of latex and resin canals that contain sticky toxins and digestibility reducers.
For example, when predators avoid a mimic that imperfectly resembles a coral snake, the mimic is sufficiently protected. [ 26 ] [ 27 ] [ 28 ] Convergent evolution is an alternative explanation for why coral reef fish have come to resemble each other; [ 29 ] [ 30 ] the same applies to benthic marine invertebrates such as sponges and nudibranchs .
This behavior may complement cryptic adaptations in the offspring themselves, such as camouflage and hiding. Mobbing calls may be used to summon nearby individuals to cooperate in the attack. Konrad Lorenz, in his book On Aggression (1966), attributed mobbing among birds and animals to instincts rooted in the Darwinian struggle to survive.
A mysterious figure who used a rare narwhal tusk to help subdue a knife-wielding extremist on London Bridge last month has been identified.
Mobbing is usually done to protect the young in social colonies. For example, red colobus monkeys exhibit mobbing when threatened by chimpanzees, a common predator. The male red colobus monkeys group together and place themselves between predators and the group's females and juveniles. The males jump together and actively bite the chimpanzees. [52]
Confused, the predator will attack the chemical mixture rather than the sea hare itself, allowing time for the sea hare to escape. [50] Several marine invertebrates are able to acquire chemical defense by covering themselves in other organisms who possess defensive secondary metabolites. This defensive mechanism is described as "chemical clothing."