Did you know that some sharks walk?
Discovered in Indonesia 2013, a species of epaulette shark Hemiscyllium halmahera, was observed using its fins to crawl along the seafloor in search of crustaceans and other invertebrates. A special adaptation allows the Epaulette sharks to also haul themselves across open air and from tidepool to tidepool. The shark, described on the Indonesian island of halmahera, uses its fins to wiggle along the seabed. The Epaulette Shark is a member of the fish family Hemiscylliidae, collectively called the Longtail Carpet Sharks.
The Epaulette Shark is a slender species that has a large black ocellus (an eye-like spot with a marginal ring) above the pectoral fin and widely spaced black spots on the body. A close relative (Hemiscyllium ocellatum), has been observed spending up to an hour on land on a single breath. Epaulette sharks likely evolved the ability to walk in the past 9 million years, scientists concluded in a 2020 study published in the journal Marine & Freshwater Research.
The study, titled “Walking, Swimming, or Hitching a Ride“, published in the journal Marine and Freshwater Research, examined nine known species of walking sharks and made interesting hypothesis about their evolution. The sharks evolved the ability to walk and survive in low oxygen environments because it helped them forage for food in environments where other sharks couldn’t survive.
The co-authors involved in the 2020 study discovered four new walking shark species in the past 12 years. Hemiscyllium is endemic to the waters of Papua, West Papua, Maluku, and North Maluku, as well as Papua New Guinea and Australia. Of the nine existing species, six are found in Indonesian waters.
Epaulette sharks are potentially forming new species at a remarkably fast rate, the study’s lead author Dr. Gavin Naylor of the Florida Museum of Natural History said in an interview with New Science. Because of the sharks’ unique mobility, small populations frequently become isolated. A river or other geographical barrier might shift enough to cut off a small group of sharks from the main population. Over time, these populations can become genetically distinct, as their genes mutate randomly and adapt separately from other gene pools, Naylor added.
The sharks can walk, but they can’t hide.
Relatively small and distinct populations place a species at higher risk to extinction from habitat loss and overharvesting.
Based on an assessment carried out in 2020, all Hemiscyllium species have been put on the red list of the International Union for Conservation of Nature (IUCN) given their vulnerability and threatened status, he noted.Two walking shark species have been declared as near threatened and three have been listed as vulnerable.
This month, Feb 23, 2023 Indonesia’s Ministry of Marine Affairs and Fisheries declared walking sharks (Hemiscyllium spp) as a fully-protected species to ensure their continued existence and to prevent their population from declining
Located in the Coral Triangle, Indonesia’s hundreds of islands hosts extraordinary marine diversity and is home to at least 218 species of sharks and rays. Indonesia is the largest shark fisher and exporter in SE Asia. Many species are threatened, including the scalloped hammerhead shark, the whale shark and the zebra shark.
The walking shark species will be one of the 20 priority fish species in the Indonesian ministry’s 2020–2024 conservation program. Shark Stewards is supporting efforts in Indonesia to protect threatened and endangered sharks by protecting their habitat in no take fishing reserves.