European grass frog

Description

The snout-vent length of adults reaches a maximum of eleven cm, with females growing slightly larger on average than males due to the slightly later onset of sexual maturity. Most specimens, however, are between seven and nine cm in size and appear quite plump. The upperparts can be yellow, red or dark brown in colour. In some animals it is only slightly marked, others have irregular black spots that can occasionally almost obscure the ground colour. The two dorsal gland bars approach each other a bit in the shoulder area. The characteristic triangular temporal spot on both sides with the tympanic membrane in it is distinctly dark brown, as in all brown frogs. The transverse striation of the hind legs is also a characteristic of all brown frogs. The male's underpart is whitish-grey and mostly unspotted, while the female's is often yellow with a reddish marbling. The tip of the snout is bluntly bevelled and rounded in plan view, the pupil is elongated and horizontally aligned. The inner metatarsal tubercle on the sole of the foot appears small and soft in this species.

The forelegs of the males are much more strongly built than those of the females. This is due to the reproductive behaviour, as the animals have to hold on to the females' backs in an axillary clasp (amplexus), sometimes for days. At spawning time, the males sometimes appear slightly "flabby" due to accumulations of lymph fluid and may even appear slightly bluish (but not as intensely as moor frog males). They develop dark, rough rutting calluses on their respective inner fingers during this phase. In females, a so-called breeding tubercles of whitish "spots" on the flanks and hind legs can be observed at spawning time.

Habitat

Spawning waters include a wide range of standing or slow-flowing waters. However, shallower, sunlit still waters such as small ponds and pools (also garden ponds) are preferred, although they are rarely allowed to dry out, or also cattle watering places in grassland areas. Floodplain grasslands, for example from the floodplain swath, are particularly popular as spawning substrates. After laying their eggs, the animals usually leave the watercourse very quickly and go over to terrestrial life. Habitats now include grassland, fringe biotopes, bushes, water banks, forests, gardens, parks and moors. At night, the frogs hunt for insects (e.g. beetles and grasshoppers), isopods, worms, spiders and slugs, during the day they hide in damp places between vegetation or under stones or deadwood. Hibernation sometimes takes place at the bottom of water bodies (then often collectively), but mainly terrestrially in holes in the ground and similar frost-free shelters. Before that, in autumn, the animals have usually already migrated some distance towards the spawning water or even use it for hibernation in cold torpor - summer habitat and hibernation quarters are therefore not necessarily identical.

The text is a translation of an excerpt from Wikipedia (https://de.wikipedia.org/wiki/Grasfrosch). On wikipedia the text is available under a „Creative Commons Attribution/Share Alike“ licence. Status: 29 June 2021