THE ANIMAL FILES

red-eyed tree frog

Agalychnis callidryas

Hatching early can escape one danger while entering another.

Red-eyed tree frogs lay eggs on leaves above or near water. Embryos respond to disturbance, and early hatching can let tadpoles drop away from an attacking egg predator. The water below is a new habitat with predators of its own.[1]

Follow the evidence ↓
red-eyed tree frog
Image: Careyjamesbalboa (Carey James Balboa) · Commons · Public domain
Egg site
Leaves above or beside water[1]
Escape
Disturbance can trigger early hatching[1]
Life stages
Leaf eggs, aquatic tadpoles, insect-eating froglets[1]

A nursery over the pond

Eggs adhere together in jelly on leaves. When they hatch, tadpoles fall into nearby water and continue development. The placement links an aerial egg stage with an aquatic larval stage. Choosing a leaf above a pond is therefore consequential even before a tadpole begins to swim.[1]

Responding to a risky vibration

Embryos can hatch early after predator disturbance. Experiments indicate that features of vibration pulses matter, rather than any motion always producing the same response. Other threats, including dehydration or flooding, can also alter timing. This is developmental plasticity: the schedule changes with environmental information.[1]

The cost of escaping

Earlier hatching reduces time exposed to egg predators but can increase vulnerability in the water. Tadpoles meet aquatic predators and have a different diet from insect-eating frogs. A successful escape response balances risks between stages; it does not make the newly hatched animal safe from every threat.[1]

A COMMON MIX-UP

Is earlier hatching always safer in every respect?

No. It can reduce egg-stage danger while increasing risk as a young tadpole.[1]

TRY A LITTLE REASONING

Why might embryos discriminate vibration patterns instead of hatching after every leaf movement?

Reveal the explanation

Unnecessary early hatching has costs; distinguishing cues helps avoid entering the water prematurely.[1]

Sources & editorial notes

Adapted and translated from the cited Wikipedia revisions, with source-linked reasoning. Image credit and licence are listed separately above.

Adapted and translated from Wikipedia contributors; exact revisions are linked below. CC BY-SA 4.0

  1. Wikipedia contributors — Agalychnis callidryas (adapted and translated; exact revision)
  2. NCBI Taxonomy — Agalychnis callidryas (identity and game lineage)

Last fact check:

One discovery leads to another

European tree frogToe discs connect a pond-breeding frog to life above the ground.Hyla arborea ↗Common toadA quiet night walk leads back to a crowded breeding pond.Bufo bufo ↗Cane toadA toad with a remarkably broad menu.Rhinella marina ↗