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Species Directory

Dusky Sea Snake

Overview Conservation & Management Resources

Dusky Sea Snake

Aipysurus fuscus

Dusky sea snake illustration. Credit: Jack Hornady.

Protected Status

ESA Endangered - Foreign
Throughout Its Range

Quick Facts

Weight
Unknown
Lifespan
10 years
Length
24 inches
Threats
Habitat degradation and loss
Region
Foreign
See Regulatory Actions

About The Species

The dusky sea snake is a marine snake found in a small number of coral reefs offshore of Western Australia in the Timor Sea. The dusky sea snake is listed as endangered throughout its range under the Endangered Species Act.

Protected Status

ESA Endangered - Foreign

  • Throughout Its Range

Appearance

The dusky sea snake is brown, or purplish-brown, with a few faint cross-bands on its sides. It has wide ventral scales and diamond-shaped body scales that are smooth and imbricate (i.e., overlapping). Imbricate scales probably help protect the snake from abrasion on sharp corals. There are generally 19 scale rows around the neck; 19 around the mid-body; and 155 or more ventral scales. There are 6 to 8 maxillary teeth behind the poison fangs. The dusky sea snake has a laterally compressed body to be used as a paddle and valvular nostrils located more dorsally. In addition to locomotion, the paddle-like tail is assumed to help with maintaining position in the water column with increased buoyancy.

Behavior and Diet

The dusky sea snake has been seen resting, swimming, or foraging between reef and sand where it preys mainly on labrid (e.g., wrasses) and gobiid (e.g., gobies) fishes, as well as fish eggs. The dusky sea snake is venomous and may stick its head or tongue into a crevice or substrate to locate prey. The specialist tendencies of the dusky sea snake make it well adapted to living on the reef, but susceptible to changes in its ecosystem.

Where They Live

The dusky sea snake is a benthic, coral reef-associated species endemic to the shallow (less than 15 meters deep), emergent reefs of the Sahul Shelf off the coast of Western Australia in the Timor Sea, between Timor and Australia. These reefs are relatively isolated and lie at the edge of the continental shelf over several hundred kilometers from the mainland.

Lifespan & Reproduction

The dusky sea snake is viviparous, which means embryos develop internally and young undergo live birth. Because this species never ventures on land, mating occurs at sea and young are born alive in the water. Within the Aipysurus genus, the number of young per female is small (usually less than four) and young are relatively large at birth. Timing and seasonality of the dusky sea snake’s breeding cycles are unknown. Little is known about the juvenile life stage of dusky sea snakes. The dusky sea snake’s lifespan is 10 years.

Threats

Habitat Degradation and Loss

Increased water temperature is a threat to the dusky sea snake and its habitat. Temperature plays a large role in the health of a reef. The heatwave that hit northwest Australia in the summer of 2015-2016 caused the waters of Scott Reef to see a 2℃ increase in temperature during this time, with 92 percent of sampled sites along this reef system being at least 60 percent bleached. This level of mortality impacts the dusky sea snake since it is only known to reside on and around hard coral reef ecosystems and impacts its ability to find shelter and prey.

Scientific Classification

Kingdom Animalia
Phylum Chordata
Class Reptilia
Order Squamata
Family Elapidae
Genus Aipysurus
Species fuscus

In the Spotlight

Management Overview

The dusky sea snake is listed as endangered under the Endangered Species Act.


Regulatory History

In 2013, NOAA Fisheries received a petition to list the dusky sea snake as threatened or endangered under the Endangered Species Act. In our 90-day finding, we concluded that the petitioned action may be warranted. After completing a status review, we proposed to list the dusky sea snake as endangered and requested comments from the public. In 2015, NOAA Fisheries listed the dusky sea snake as endangered under the Endangered Species Act.

Key Actions and Documents

Actions & Documents Incidental Take

Dusky Sea Snake 5-Year Review

In 2020, NMFS announced the initiation of a 5-year review for the dusky sea snake (Aipysurus fuscus). NMFS is required by the Endangered Species Act (ESA) to conduct 5-year reviews to ensure that the listing classifications of species are…
  • Notice of Initiation of a 5-Year Review (85 FR 40622, 7/7/2020)
  • Dusky Sea Snake 5-Year Review (2020)
Notice
,
Foreign
Published
September 16, 2020

Final Rule To List the Dusky Sea Snake and Three Foreign Corals Under the Endangered Species Act

We, NOAA Fisheries, issue a final rule to list three foreign corals and the dusky sea snake under the Endangered Species Act (ESA). We considered comments submitted on the proposed listing rule and have determined that the three foreign corals …
  • Final Rule (80 FR 60560, 10/07/2015)
  • 12-Month Finding and Proposed Rule (79 FR 74953,12/16/2014)
  • 90-Day Finding (78 FR 63941, 10/25/2013)
  • Petition to List 81 Marine Species Under the ESA (2013)
  • Status Review Report of 3 Species of Foreign Corals; Cantharellus noumeae, Side…
  • Status Review Report for the Dusky Sea Snake
Final Rule
,
National
Foreign
Effective
11/06/2015

More Information

  • Listing Foreign Species Under the ESA

Science Overview

Documents

Document

Dusky Sea Snake 5-Year Review

A 5-year review is a periodic analysis of a species’ status conducted to ensure the accuracy of…

International
Document

Status Review Report for the Dusky Sea Snake (Aipysurus fuscus)

The August 2014 status review report conducted in response to a petition to list to list 81 marine…

International
More Documents
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