What is the phenomenon when animals mimic other animals in order to survive?

Question

The caterpillar Hemeroplanes triptolemus adopts the appearance of a snake when it detects danger. What is this phenomenon called in which animals mimic other animals in order to survive? Is it morphological adaptation, if not why not?

Answer 1

Deimatic display:

Deimatic behaviour or startle display means any pattern of bluffing behaviour in an animal that lacks strong defences, such as suddenly displaying conspicuous eyespots, to scare off or momentarily distract a predator, thus giving the prey animal an opportunity to escape.

This could also be referred to in more general terms as Batesian mimicry.

In Batesian mimicry the mimic shares signals similar to the model, but does not have the attribute that makes it unprofitable to predators (e.g., unpalatability). In other words, a Batesian mimic is a sheep in wolf's clothing. It is named after Henry Walter Bates, an English naturalist whose work on butterflies in the Amazon rainforest (described in The Naturalist on the River Amazons) was pioneering in this field of study.

This is distinct from aposematism, in which a positive defence mechanism is present and advertised:

Aposematism is the advertising by an animal to potential predators that it is not worth attacking or eating. This unprofitability may consist of any defences which make the prey difficult to kill and eat, such as toxicity, venom, foul taste or smell, sharp spines, or aggressive nature. These advertising signals may take the form of conspicuous coloration, sounds, odours, or other perceivable characteristics.

Answer 2

The phenomenon whereby one animal mimics another is called mimicry by zoologists as opposed to camouflage, although plants can be mimcs as well.

There are this many varieties of mimicry, so it's best to refer to the wiki reference:

2.1 Defensive
    Batesian
    Müllerian
    Emsleyan/Mertensian
    Wasmannian
    Vavilovian
    Gilbertian
    Browerian
2.2 Aggressive
    Predators
    Parasites
2.3 Reproductive
    Bakerian and Dodsonian
    Pseudocopulation
    Inter-sexual mimicry
2.4 Automimicry

https://en.wikipedia.org/wiki/Mimicry

Is it a morphological adaptation? It effects pigmentaiton and morphology and it is encouraged by random mutations which confer to the mimic a resemblance which has an evolutionary advantage, i.e. a resemblance to an animal which is avoided by predators.