is Phyllobates terribilis. It is argued that dart frogs do not synthesize their poisons, but sequester the chemicals from arthropod prey items, such as ants, centipedes and mites – the diet-toxicity hypothesis. Because of this, captive-bred animals do not possess significant levels of toxins as they are reared on diets that do not contain the alkaloids sequestered by wild populations. In fact, new studies suggest that the maternal frogs of some species lay unfertilized eggs, which are laced with trace amounts of alkaloids, to feed the tadpoles. This behavior shows that the poisons are introduced from a very young age. Nonetheless, the captive-bred frogs retain the ability to accumulate alkaloids when they are once again provided an alkaloidal diet. Despite the toxins used by some poison dart frogs, some predators have developed the ability to withstand them. One is the snake Erythrolamprus epinephalus, which has developed immunity to the poison. Chemicals extracted from the skin of Epipedobates tricolor may have medicinal value. Scientists use this poison to make a painkiller. One such chemical is a painkiller 200 times as potent as morphine, called epibatidine; however, the therapeutic dose is very close to the fatal dose. A derivative ABT-594 developed by Abbott Laboratories, called Tebanicline got as far as Phase II trials in humans, but was dropped from further development due to dangerous gastrointestinal side effects. Secretions from dendrobatids are also showing promise as muscle relaxants, heart stimulants and appetite suppressants. The most poisonous of these frogs, the golden poison frog (Phyllobates terribilis), has enough toxin on average to kill ten to twenty men or about twenty thousand mice. Most other dendrobatids, while colorful and toxic enough to discourage predation, pose far less risk to humans or other large animals. Conspicuousness Conspicuous coloration in these frogs is further associated with diet specialization, body mass, aerobic capacity, and chemical defense. Conspicuousness and toxicity may be inversely related, as polymorphic poison dart frogs that are less conspicuous are more toxic than the brightest and most conspicuous species. Energetic costs of producing toxins and bright color pigments lead to potential trade-offs between toxicity and bright coloration, and prey with strong secondary defenses have less to gain from costly signaling. Therefore, prey populations that are more toxic are predicted to manifest less bright signals, opposing the classical view that increased conspicuousness always evolves with increased toxicity. Aposematism Skin toxicity evolved alongside bright coloration, perhaps preceding