# Sea Snake — Facts, Threats & Conservation *Subfamily Hydrophiinae — roughly 70 species of fully marine elapid snakes* > Sea snakes (subfamily Hydrophiinae) are roughly 70 species of fully marine venomous elapid with paddle tails and salt-excreting glands — among the most venomous snakes, generally inoffensive to humans, and vulnerable to trawl bycatch. **IUCN status:** Group page — most species unassessed; some face bycatch and habitat degradation · **WARN range:** Indian Ocean and Pacific Ocean, Tropical and subtropical coastal waters; absent from the Atlantic ## Quick facts | Fact | Value | | --- | --- | | Species count | ~70 | | Range | Indo-Pacific only | | Tail | Paddle-shaped for swimming | | Venom | Highly neurotoxic | | Reproduction | Live-bearing in most species | | Main threats | Trawl bycatch, reef degradation | ## Scientific classification - **Kingdom:** Animalia - **Phylum:** Chordata - **Class:** Reptilia - **Order:** Squamata - **Family:** Elapidae - **Subfamily:** Hydrophiinae — ~70 species ## Conservation status - **Status:** Varies by species — group page - **Population:** Unknown for most species - **Trend:** Suspected declining where bycatch and reef loss are high - **Assessed:** Most species unassessed - **CITES:** Some species listed - Bycatch mortality likely exceeds targeted conservation attention. Reef protection and fisheries observer data are the practical levers. ## Key facts: Sea Snake - Sea snakes are elapids adapted for full marine life — paddle tail, valved nostrils, extended lungs. - All are venomous; potency is high but bites to humans are rare and usually involve handling. - They occur only in the Indian and Pacific Oceans — none in the Atlantic. - Salt glands under the tongue help excrete sodium from ingested seawater. - Trawl fishery bycatch is a major source of mortality, often unrecorded. - Most species are unassessed by the IUCN; reef health and fisheries policy are conservation levers. ## Anatomy of a marine elapid Sea snakes lost the terrestrial elapid body plan for one optimised to water. The tail is the primary propulsive surface — flattened sideways like an oar. Ventral scales are reduced; the body is round in cross-section. Nostrils close with valves during dives. Some species remain submerged for hours, absorbing oxygen through the skin supplementing lung stores — a capacity that varies by species and temperature. Salt excretion is critical. Drinking seawater would dehydrate a reptile without removal of excess salt. Sub lingual glands secrete a concentrated brine that the snake expels, maintaining electrolyte balance. Reproduction is live-bearing in most species — sea kraits and some hydrophiines come ashore to lay, but true pelagic sea snakes give birth at sea. Colour patterns are often bold — bands of black and yellow, blue-grey overlays — which may serve aposematic warning given toxicity to predators. Fish prey do not learn the signal; bird and larger fish predators may. ## Venom, bites and the handling risk Sea snake venom is predominantly neurotoxic, causing muscle pain, stiffness and potentially paralysis. Potency measured in laboratory tests exceeds many terrestrial elapids, reflecting the need to immobilise fish quickly. Fang size is small relative to cobras; envenomation requires prolonged contact in some cases, which is why fishermen sorting catch by hand are the typical bite victims. Defensive biting at divers is uncommon. Sea snakes investigate curiously but rarely strike unless grabbed. Antivenom exists where sea snake fisheries overlap human populations — notably northern Australia and Southeast Asia — but must be species-appropriate where possible. First aid mirrors other neurotoxic snakebites: urgent hospital care, antivenom if available, supportive ventilation if needed. Prevention is gloves and tools when handling nets, not killing snakes at sea. ## Fisheries bycatch and silent mortality Trawl nets scoop sea snakes along with target fish across tropical fisheries. Brought to the surface, snakes may be dead or dying; many are discarded overboard uncounted. Estimates of annual bycatch reach tens of thousands in single regional fisheries, yet reporting is sparse because sea snakes have no commercial value and no constituency in catch statistics. Reduction devices — exclusion grids, net modifications, spatial closures — can lower bycatch where implemented. Turtle excluder devices adapted for snakes have been trialled in some fisheries. Without pressure, bycatch continues as background mortality eroding populations that reproduce slowly — many sea snakes mature late and produce small litters. Linking sea snake monitoring to existing fisheries observer programmes would cost little relative to the information gained. Currently, population trends for most species are guesses inferred from catch rates and anecdotal diver sightings. ## Reef dependence and climate pressure Sea snakes feed on small fish, eels and fish eggs associated with coral reefs, seagrass and estuaries. Reef degradation from warming, acidification, pollution and dynamite fishing reduces prey density. Sedimentation smothers seagrass beds used by some species. The snakes are indicators of reef productivity — abundant sea snakes usually mean a functioning fish community below. Climate change adds thermal stress directly. Sea snakes are ectotherms with upper temperature tolerances; shallow water warming may exceed preferred ranges in some regions, forcing depth shifts or local extirpation. Oxygen minimum zones expanding in tropical seas add another stress layer for air-breathing divers. Conservation is therefore reef conservation plus fisheries reform — not snake-specific reserves. Marine protected areas that recover fish stocks benefit sea snakes as a side effect. Species-level Red List assessments lag; filling that gap is prerequisite to arguing for bycatch reduction in international fisheries forums. ## Sea kraits versus true sea snakes Not every marine elapid is fully pelagic. Sea kraits in genus Laticauda retain land dependency — they must come ashore to lay eggs and to drink freshwater when available. They forage at sea but return to coastlines, making them vulnerable to coastal development and egg predation on beaches. True hydrophiine sea snakes give birth at sea and may never voluntarily beach. The distinction matters for conservation planning: sea krait protection requires terrestrial nesting habitat; hydrophiine protection requires fisheries and reef management. Both groups share venom potency and bycatch vulnerability. Diver education in Indo-Pacific tourism hubs — look but do not grab, even when snakes appear docile on the bottom — reduces handling bites without harming snake populations. ## What WARN does WARN publishes free, sourced species education for marine life killed as collateral rather than targeted. Sea snake bycatch is invisible in most statistics — making it visible is step one toward net reform. If this guide helps you understand wildlife and the pressures it faces, a gift to WARN supports habitat protection and free public education in our partner countries. ## Frequently asked questions: Sea Snake ### Are sea snakes venomous? Yes — all roughly 70 species are venomous elapids. Potency is among the highest of any snake, but bites to humans are rare unless snakes are handled, as in fishing nets. ### Do sea snakes come on land? Most hydrophiine sea snakes never voluntarily come ashore. Sea kraits (genus Laticauda) must come ashore to lay eggs and rest. ### Where are sea snakes found? Tropical and subtropical Indian and Pacific Oceans — from the Persian Gulf to the Pacific islands. None occur in the Atlantic. ### How do sea snakes drink? They ingest seawater and excrete excess salt through sublingual salt glands. Freshwater layers from rain or river outflow may also be used where available. ### Are sea snakes aggressive to divers? Generally no. Curious approaches occur but defensive bites are uncommon. Risk rises sharply when snakes are caught or handled. ### What do sea snakes eat? Sea Snakes eat Bycatch — Major undocumented mortality in trawl fisheries. Sea snakes (subfamily Hydrophiinae) are roughly 70 species of fully marine venomous elapid with paddle tails and salt-excreting glands — among the most venomous snakes, generally inoffensive to humans, and vulnerable to trawl bycatch. ### Where do sea snakes live? Sea Snakes live in Indo-Pacific only. Sea snakes (subfamily Hydrophiinae) are roughly 70 species of fully marine venomous elapid with paddle tails and salt-excreting glands — among the most venomous snakes, generally inoffensive to humans, and vulnerable to trawl bycatch. ### How long do sea snakes live? A precise wild lifespan for sea snakes is not firmly established in the sources cited on this guide. Sea snakes (subfamily Hydrophiinae) are roughly 70 species of fully marine venomous elapid with paddle tails and salt-excreting glands — among the most venomous snakes, generally inoffensive to humans, and vulnerable to trawl bycatch. Where longevity figures appear in the literature they vary by region, sex and whether animals are wild or captive. ### How big is a sea snake? A Sea Snake is about Paddle tail (Laterally flattened for swimming). Sea snakes (subfamily Hydrophiinae) are roughly 70 species of fully marine venomous elapid with paddle tails and salt-excreting glands — among the most venomous snakes, generally inoffensive to humans, and vulnerable to trawl bycatch. Conservation status: Trawl bycatch, reef degradation. ## Sources - [IUCN Red List](https://www.iucnredlist.org/) - [Sea Snakes — Australian Museum](https://australian.museum/learn/animals/fishes/sea-snakes/) --- Full guide: https://worldanimalrescuenetwork.org/wildlife-guides/sea-snake