Dolphins

Details

Delphinidae (the oceanic dolphins) is the largest and most widespread family of toothed whales, including true dolphins, killer whales (orcas), false killer whales, spinner dolphins, bottlenose dolphins and many others (~30+ genera, ~90+ species). They are noted for advanced sociality, echolocation and complex behaviours, occupying key predatory niches from coasts to the high seas.

Ecology & Behaviour

• Diet: mainly fishes and cephalopods; large species (e.g., orcas) also take marine mammals and seabirds.

• Society: group sizes from small pods to megagroups; matrilines/mixed kin networks; cooperative hunting, cultural transmission and dialects.

• Echolocation: a focused biosonar produced by the melon; diverse call repertoires across taxa.

• Movements: seasonal migrations in some populations; coexistence of resident/offshore/coastal ecotypes.

Identification (family‑level)

Body lengths span ~1.2–9 m (orcas largest). Streamlined bodies with a distinct dorsal fin and a variable rostrum (short in orcas); numerous conical teeth; single blowhole; blubber and muscle specializations for sustained, high‑speed swimming.

Size & Longevity (family range)

• Length: ~1.2–9.0 m.

• Mass: ~40 kg to >6,000 kg (orcas).

• Life: small dolphins 20–40 yrs; large taxa (e.g., orcas) 60–90+ yrs.

Range & Habitat

Nearly global oceans except some enclosed polar seas; from coastal shelves/estuaries to pelagic and deep‑ocean habitats. Coastal taxa track estuaries/upwelling/fronts; offshore taxa associate with warm pools, eddies and frontal systems.

Threats & Conservation

• Bycatch/entanglement in gillnets/longlines/purse seines; acoustic pingers, weak links and handling protocols reduce mortality.

• Noise & vessels: shipping, military sonar and seismic surveys disrupt communication/foraging; vessel strikes occur.

• Pollution & food‑web change: POPs, plastics/microplastics and climate‑driven shifts in prey fields.

• Poorly managed tourism: close approaches, feeding and crowding alter behaviour and energy budgets.

IUCN: This is a family overview—Not evaluated as a whole; categories vary widely by species/population (LC–CR). Priorities include gear modification/avoidance, noise management, vessel speed/routing, spatio‑temporal protection of key habitats and corridors, and long‑term photo‑ID/acoustic monitoring with citizen‑science inputs.