First recorded from a specimen collected in Hawaiʻi in 1841, the species was originally described as a member of the dolphin family and named Lagenorhynchus electra by John Edward Gray in 1846.

Compared to females, adult males have more rounded heads, longer flippers, taller dorsal fins, broader tail flukes and some have a pronounced ventral keel posterior to the anus.

[6][7][8] Melon-headed whales grow up to 2.75 m (9.0 ft) in length, and weigh up to 225 kg (496 lb), adult males being slightly larger than females.

[9] Although considered an offshore pelagic species, in some regions there are island-associated populations (e.g., Hawaiʻi) and they can be found close to shore associated with oceanic islands and archipelagoes, such as Palmyra and the Philippines.

[11] However, genetic studies of melon-headed whales across the Pacific, Indian and Atlantic Ocean basins suggest that there is relatively high level of connectivity (inter-breeding) between populations.

[19] Larger group sizes may increase competition for prey resources, requiring large home ranges and broad-scale foraging movements.

[19] Observations of daily activity patterns of melon-headed whales near oceanic islands suggest they spend the mornings resting or logging in near-surface waters after foraging at night.

[15] Surface activity (such as tail slapping and spyhopping) and vocalizations associated with socializing (communication whistles, rather than echolocation clicks used for foraging) increase during the afternoons.

[15][20] The daily pattern of behavior observed in island-associated populations, combined with the larger group sizes of melon-headed whales (compared to that typically seen in other blackfish species) is more similar to the fission-fusion social structure of spinner dolphins (Stenella longirostris).

[21][22] A unique case of inter-species adoption between (presumably) an orphaned melon-headed whale calf and a common bottlenose dolphin mother was recorded in French Polynesia.

Genetic testing of a skin biopsy sample confirmed that the individual was a hybrid between a female melon-headed whale and a rough-toothed dolphin male.

[25][26] Scars and wounds from non-lethal bites of cookie cutter sharks (Isitius brasiliensis) have been observed on free-ranging and stranded animals.

The most information comes from analyses of large stranding groups in Japanese waters, where sexual maturity for females is reached at 7 years of age.

[10] Melon-headed whales are known to mass strand, often in groups numbering in the hundreds, indicative of the strong social bonds within herds of this species.

[17] Mass strandings of melon-headed whales have been reported in Hawaiʻi, eastern Japan, the Philippines, northern Australia, Madagascar, Brazil and the Cape Verde Islands.

[38] Individuals are taken for bait or human consumption in small cetacean subsistence and harpoon fisheries in several regions, including Sri Lanka,[34] the Caribbean,[39] the Philippines [40] and Indonesia.

[41] At Dixcove port in Ghana, melon-headed whales are the third highest cetacean species caught for ‘marine bushmeat’ by artisanal fishermen, through both bycatch from drift gillnets and occasional directed catch.

Persistent organic pollutants (POPs)–include environmental contaminants such as polychlorinated biphenyls (PCBs), organochlorine pesticides e.g. dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs) and organobromine compounds such as polybrominated diphenyl ethers (PBDEs)–are lipophilic (fat-soluble) and can accumulate in the blubber of marine mammals.

[46][47] Blubber samples from melon-headed whales stranded in Japan and Hawaiʻi were found to have PCB concentrations above thresholds considered toxic.

[50] Melon-headed whales may be vulnerable to impacts from anthropogenic (human generated) noise, such as those associated with military sonar activities, seismic surveys and high power multi-beam echosounder operations.

[51] For island-associated populations, such as those in the Hawaiian archipelago,[21] Palmyra Atoll and the Marquesas Islands,[15] exposure to anthropogenic noise could result in displacement from important habitat.