History and origin
The Marsh frog was first described by Pallas in 1771, the scientific name of this species is Pelophylax ridibundus. Pelophylax is from Greek and is composed of two words, the first is 'mud' and the second is 'guardian' name given because these frogs never move far away from the water and they often stay immobile on the waters edge as if they were guarding the mud. Ridibundus is from Latin and means 'to laugh in busts', 'to bust with laughter' illusion of their call.

Characteristics
They are the largest native frog in France, identification can be very difficult if they are within the Pelophylax perezi size range.

Description
=Size=
- Eggs: The eggs measure about 6 to 8 mm in diameter.
- Tadpoles: The tadpoles measure about 4 to 8 mm long when they first hatch, reaching a size of about 50 to 70 mm long before metamorphose, in the case of a hibernating tadpole, their size may be as long as 100 mm.
- Juveniles: The juveniles measure 16 to 25 mm long at least when they exit the water.
- Adults: They usually grow up to 140 mm long, however sometimes they can grow to about 780 mm long.
=Morphology=
- Eggs: They are laid in separate balls in a single cluster of up to 16000 eggs.
- Tadpoles: They do not have a very tall tail, it ends in a rounded manor. Their tail does not come up onto the back.
- Adults: They are a very large, heavily built frog, their snout is large and rounded, they have ripely skin and prominent dorsolateral folds. The hind feet webbing is very complete. They do not have paratoid glands, their pupils are horizontal, males have a pair of external vocal sacs.
=Patterns & colours=
- Eggs: They are brownish on top and creamy or white on the underside.
- Tadpoles: They are greyish, brownish... their bellies are light creamy.
- Adults: They are very variable, in fact so variable that this is not a significant for identification, they can be uniform, dark in colour, or yellowish with regular or irregular dark spots or blotches. This species often has a light line running down the back. Their belly is whitish sometimes speckled with darker blotches. Their eyes are golden.

Geographical range
Their distribution is very scattered, over Europe, they are absent from Spain and Portugal, Italy, and from all Mediterranean islands.

Subspecies
None described.

Sexual differences
Males have nuptial pads on their hands which are greyish in colour. Males have a pair of external vocal sacs.

Seasonal variations
Males nuptial pads cary in colour being darker during the breeding season. They are darker just after coming out of hibernation.

Diet
They feed on ground invertebrate, spiders, insects, water insects, moths, flies... fish, newts, sometimes the same species, small birds... Tadpoles eat mainly vegetation but also ants and micro-organisms.

Defensive habits
They will emit a defensive call if caught, otherwise they will jump into the water and hide.

Reproduction
The breeding season can last up to 1 to 2 months. Reproduction sites are still water holes, in ponds, lakes or in swamps... Males are seen sitting on an algae rock singing at each other as if they are running a singing competition. When a female comes within eye distance of our singing males, the singing stops and the most impatient males immediately swim over to her, they then take the female to an area in the water with many plants, sticks and in general a lot of vegetation. Then there is another competition between the males, but this time there's a judge, the female. They sing at each other an the one who has the most piercing sound should normally win the females wishes to breed. the winning male will climb onto the females back and hold her behind her front legs, the male wraps his arms around her and sometimes the males thumbs will come into contact. The female will then eject a small clutch of eggs which the male fertilizes on their way out of the female. After a short pause, the same happens again. If they are disturbed they will dive and separate, often swimming in the opposite direction, if the female comes to the surface and can't see the male she was just with, she will take another male and this procedure will reproduce until the female is empty.
This species interbreeds with: Pelophylax perezi, creating Pelophylax kl. grafi and with Pelophylax lessonae, creating Pelophylax kl. esculentus

Sexual maturity, life span
The average life span for Pelophylax ridibundus is about 11 years, they reach their sexual maturity in their second year for males and in their third for females.

Habits
Active by day, they are very aquatic and spend all of their time in or within a jumping distance to the water. Hibernates in water. They are not found further then 5 m from water.

Call
A rapid laughing sound like 're...re...re...' up to 30 notes a second, each croak lasts for up to a 1.5 seconds, sound (p)www.oreilleverte.com:

Habitat
They live all year round in or around the water, they are the most common in calm parts of rivers, but also found in isolated ponds ad other wet areas. They are very common in slow flowing waterways. They seem to prefer more open areas. They hibernate in the water.

Predators
They are hunted by both Natrix species, the owl and many aquatic birds.