Green-and-black Poison-dart Frog

Green-and-black Poison-dart Frog

Also known / common namesSpanish – Rana venenosa verde y negra; “Green Poison Frog”

Green-and-black Poison-dart Frog(s) General Description

Small diurnal dendrobatid (SVL 18–40 mm, mass ≈ 1–3 g) with smooth, glandular skin containing alkaloid toxins. Ground colour black or dark chocolate overlain by bright green, turquoise or mint-blue irregular blotches; Pacific morphs often bronze-black with lime spots. Digits bear expanded adhesive discs; toes basally webbed. Iris dark; tympanum distinct. Females generally 10 % larger. Tadpoles grey-brown with high fins and conspicuous eyes. Colour changes little after metamorphosis.

Has Sexual Diamorphism?

Females larger; males have swollen third-finger pads and produce 3-kHz trilling calls.

LIFE‑HISTORY & VITAL STATISTICS OF THE Green-and-black Poison-dart Frog(S)

Average Height / Length / Diameter

Males 2.2 cm; females 2.5 cm SVL

Average Adult Weight / Mass

≈ 2 g

Typical Lifespan / Longevity

4–8 yr wild; up to 12 yr captivity

Typical Lifespan / Longevity for males

No data

Typical Lifespan / Longevity for Females

No data

Age at Sexual Maturity

≈ 9–12 mo

Breading Season

Extended rainy season (May – Nov)

Gestation

Reproductive Outcome

Eggs hatch 7–12 d; tadpoles metamorphose 6–8 wk

Ecology and Behaviour for Green-and-black Poison-dart Frog(s)

Small diurnal dendrobatid (SVL 18–40 mm, mass ≈ 1–3 g) with smooth, glandular skin containing alkaloid toxins. Ground colour black or dark chocolate overlain by bright green, turquoise or mint-blue irregular blotches; Pacific morphs often bronze-black with lime spots. Digits bear expanded adhesive discs; toes basally webbed. Iris dark; tympanum distinct. Females generally 10 % larger. Tadpoles grey-brown with high fins and conspicuous eyes. Colour changes little after metamorphosis.

Habitat

Humid lowland & premontane rain forest (0–800 m) on both coasts; abundant in shaded cacao/banana plantations and secondary forest near permanent water.

Trophic Chain

Diurnal leaf-litter insectivore specialising on formicine ants & mites—the alkaloid source.

Interespecies relationships noted for Green-and-black Poison-dart Frog

Mutualism +/+

Bromeliads & Heliconia leaf-axils: tadpoles excrete nitrogenous waste that fertilises the plant’s tiny water reservoirs; frog gains predator-free nurseries.

Symbiosis +/+

Skin microbiome dominated by Janthinobacterium spp. produces violacein, inhibiting chytrid fungus; bacteria receive habitat and nutrients in skin mucus.

Commensalism +/0

Tiny phorid flies oviposit on abandoned egg capsules; larvae feed on residual jelly without harming frog offspring.

Inquilinism + / 0

Mite (Parasitellus) deutonymphs attach to frog’s skin folds during dispersal, gaining moist transport; frog experiences negligible cost.

Phoresy + / 0

Occasionally, fungal spores of Beauveria hitchhike on sticky skin but do not germinate until frog contacts leaf litter, gaining dispersal mileage.

Tanatocresis + / 0

Decomposed egg masses enrich micro-patches, promoting colonisation by saprotrophic fungi (Trichoderma) that later support detritivorous springtails; frog already metamorphosed.

Parasitism + / –

Lung nematode Rhabdias breviensis reduces male call rate and clutch size.

Predation +/-

Cat-eyed snake (Leptodeira septentrionalis) tolerates alkaloids and preys on both adults and egg clutches.

Amensalism 0 / –

Alkaloid-rich mucus sloughed onto leaves suppresses nearby saprotrophic fungi, gaining no further benefit to frog.

Competition -/-

Shares bromeliad nursery pools with Blue-black grassquit tadpoles (Oophaga pumilio in overlap zones), leading to food limitation and cannibalism.

Social behaviour of Green-and-black Poison-dart Frog

  • Males defend 1–2 m² leaf-litter territories; aggressive wrestling common.

  • Courtship involves tactile nudging to suitable oviposition site (leaf axil).

  • Male guards eggs, hydrates clutch; carries tadpoles to tree-holes/bromeliads

Distribution and Sighthings ofGreen-and-black Poison-dart Frog(s) in Costa Rica

General Regions of Costa Rica where to find Green-and-black Poison-dart Frogs

Tropical
Tropical rainforest (Caribbean and North Pacific slopes)

National Parks and Reserves of Costa Rica where to find Green-and-black Poison-dart Frogs

Parque Nacional Braulio Carrillo
Parque Nacional Cahuita
Parque Nacional Tortuguero
Reserva Biológica Hitoy-Cerere
Refugio Nacional de Vida Silvestre Gandoca-Manzanillo

Best Time to seeGreen-and-black Poison-dart Frog(s) in Costa Rica

Dry Season
January
February
March
April
June
July
August
September
October
November
December

Media

Videos

Sounds and calls

Taxonomy

Conservation Status

Status IUCN

Threats

⚠️Forest conversion to pineapple & oil-palm diminishes leaf-litter humidity.
⚠️Illegal pet trade (bright morphs).
⚠️Agricultural pesticides lowering alkaloid-bearing prey abundance.
⚠️Climate-driven desiccation of phytotelmata nursery sites.

Fun Facts

  • Introduced to O‘ahu, Hawai‘i, in 1932 to control mosquitoes; now naturalised.
  • Exhibits Müllerian mimicry with Oophaga pumilio where ranges overlap.

  • Tadpoles are omnivorous cannibals if multiple share a pool.

  • Male territorial call rate increases after rain-onset acoustic cues.

Origins & Record

Origin Status

Native

Population trend

Decreasing

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