Monarch butterfly in the context of List of butterflies of North America

Quadrupedalism is a form of locomotion in which animals have four legs that are used to bear weight and move around. An animal or machine that usually maintains a four-legged posture and moves using all four legs is said to be a quadruped (from Latin quattuor for "four", and pes, pedis for "foot"). Quadruped animals are found among both vertebrates and invertebrates.

Caterpillars (/ˈkætərpɪlər/ KAT-ər-pil-ər) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths).

As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Symphyta) are commonly called caterpillars as well. Both lepidopteran and symphytan larvae have eruciform body shapes.

In zoology, automimicry, Browerian mimicry, or intraspecific mimicry, is a form of mimicry in which the same species of animal is imitated. There are two different forms.

In one form, first described by Lincoln Brower in 1967, weakly-defended members of a species with warning coloration are parasitic on more strongly-defended members of their species, mimicking them to provide the negative reinforcement learning required for warning signals to function. The mechanism, analogous to Batesian mimicry, is found in insects such as the monarch butterfly.

In conservation biology, a flagship species is a species chosen to raise support for biodiversity conservation in a given place or social context. Definitions have varied, but they have tended to focus on the strategic goals and the socio-economic nature of the concept, to support the marketing of a conservation effort. The species need to be popular, to work as symbols or icons, and to stimulate people to provide money or support.

Species selected since the idea was developed in 1980s include widely recognised and charismatic species like the black rhinoceros, the Bengal tiger, and the Asian elephant. Some species such as the Chesapeake blue crab and the Pemba flying fox, the former of which is locally significant to Northern America, have suited a cultural and social context. Although animal species that can be described as "charismatic megafauna" are frequently the flagship species for a protected ecosystem, large, dominant plant species sometimes serve this role as well, for example, several United States national parks, including Redwood National and State Parks, Joshua Tree National Park, and Saguaro National Park, are named for the flagship plant species for those protected areas. Butterfly species, such as the monarch butterfly, have also served as flagship species in some contexts.

Whether invertebrates can feel pain is a contentious issue. Although there are numerous definitions of pain, almost all involve two key components. First, nociception is required. This is the ability to detect noxious stimuli which evokes a reflex response that moves the entire animal, or the affected part of its body, away from the source of the stimulus. The concept of nociception does not necessarily imply any adverse, subjective feeling; it is a reflex action. The second component is the experience of "pain" itself, or suffering—i.e., the internal, emotional interpretation of the nociceptive experience. Pain is therefore a private, emotional experience. Pain cannot be directly measured in other animals, including other humans; responses to putatively painful stimuli can be measured, but not the experience itself. To address this problem when assessing the capacity of other species to experience pain, argument-by-analogy is used. This is based on the principle that if a non-human animal's responses to stimuli are similar to those of humans, it is likely to have had an analogous experience. It has been argued that if a pin is stuck in a chimpanzee's finger and they rapidly withdraw their hand, then argument-by-analogy implies that like humans, they felt pain. It has been questioned why the inference does not then follow that a cockroach experiences pain when it writhes after being stuck with a pin. This argument-by-analogy approach to the concept of pain in invertebrates has been followed by others.

The ability to experience nociception has been subject to natural selection and offers the advantage of reducing further harm to the organism. While it might be expected therefore that nociception is widespread and robust, nociception varies across species. For example, the chemical capsaicin is commonly used as a noxious stimulus in experiments with mammals; however, the African naked mole-rat, Heterocephalus glaber, an unusual rodent species that lacks pain-related neuropeptides (e.g., substance P) in cutaneous sensory fibres, shows a unique and remarkable lack of pain-related behaviours to acid and capsaicin. Similarly, capsaicin triggers nociceptors in some invertebrates, but this substance is not noxious to Drosophila melanogaster (the common fruit fly).Criteria that may indicate a potential for experiencing pain include:

Insect migration is the seasonal movement of insects, particularly those by species of dragonflies, beetles, butterflies and moths. The distance can vary with species and in most cases, these movements involve large numbers of individuals. In some cases, the individuals that migrate in one direction may not return and the next generation may instead migrate in the opposite direction. This is a significant difference from bird migration.