page_title: Defence against herbivory
section_title: Records of herbivores
hierarchical_section_title: Defence against herbivory / Evolution of defensive traits / Records of herbivores
caption_attribution_description: Plain tiger caterpillar in first instar. creating a moat on leaf of calotropis gigantia
context_page_description: Defence against herbivory describes plant defences to avoid being eaten. There are many adaptations which improve the survival and reproduction of plants by reducing the impact of herbivores.
  Many plants produce chemicals which change the behaviour, growth, or survival of herbivores. These chemical defences can act as repellents or toxins to herbivores, or reduce plant digestibility. Some plants, known as hyperaccumulators, specialise in storing heavy metals which are toxic to animals.
  Some plants encourage the presence of natural enemies of herbivores, which in turn protect the plant. Some plants provide a home for ants which defend the plant strongly.
  Other defensive strategies used by plants include escaping or avoiding herbivores in time or in place. They may grow where plants are not easily found or got at by herbivores. They may grow when herbivores are not around. Herbivores may get diverted towards non-essential parts, or a plant may be able to recover from the damage caused by herbivory.
  Each type of defence can be either constitutive, or induced. Plants can and do react to damage.
context_section_description: Our understanding 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 coprolite (animal faeces); and
  the construction of herbivore mouthparts.
  Long thought to be a Mesozoic phenomenon, evidence for herbivory is found almost as soon as fossils which could show it. Within under 20 million years of the first fossils of sporangia and stems towards the close of the Silurian, around 420 mya, there is evidence that they were being eaten. Animals fed on the spores of early Devonian plants, and the Rhynie chert also provides evidence that organisms fed on plants using a "pierce and suck" technique.  Many plants of this time are preserved with spine-like growths, which may have had a defensive role.
  During the ensuing 75 million years, plants evolved a range of more complex organs – from roots to seeds.  There was a gap of 50 to 100 million years between each organ evolving, and it being fed upon.  Hole feeding and skeletonization are recorded in the early Permian, with surface fluid feeding evolving by the end of that period.
caption: A plain tiger caterpillar Danaus chrysippus making a moat to block defensive chemicals of Calotropis before feeding
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