Flip Nicklin / Humpback Whale (Megaptera novaeangliae) friendly singer approaches hydrophone, Maui, Hawaii - notice must accompany publication; photo obtained under NMFS permit 987

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) below hydrophone dangling from research boat, Maui, Hawaii - notice must accompany publication; photo obtained under NMFS permit 0753-1599

Flip Nicklin / Sperm Whale (Physeter macrocephalus) researchers Steve Dawson and Elizabeth Slooten using hydrophones to listen to whale vocalizations, New Zealand

Flip Nicklin / Narwhal (Monodon monoceros) researchers recording vocalizations, Baffin Island, Canada

Juergen Freund / Dwarf minke whale {Balaenoptera acutorostrata} passing hydrophone of the boat 'Undersea Explorer' Great Barrier Reef, Queensland, Australia

Flip Nicklin / Sperm Whale (Physeter macrocephalus) researcher Jonathan Gordon on board, recording songs of the whale using a hydrophone to listen for whales, Dominica

Flip Nicklin / Sperm Whale (Physeter macrocephalus) researcher listening for vocalizations, New Zealand

Flip Nicklin / Bottlenose Dolphin (Tursiops truncatus) wearing hydrophone, Florida

Flip Nicklin / Sperm Whale (Physeter macrocephalus) researcher recording communication, Sri Lanka

Flip Nicklin / Sperm Whale (Physeter macrocephalus) researcher, Hal Whitehead, listening for whales with hydrophone, Sri Lanka

Flip Nicklin / Dwarf Minke Whale (Balaenoptera acutorostrata) near hydrophone, Western Australia

Flip Nicklin / Sperm Whale (Physeter macrocephalus) researcher Hal Whitehead listening to vocalizations on hydrophone, Sri Lanka

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) near hydrophone dangling from research boat, Maui, Hawaii - notice must accompany publication; photo obtained under NMFS permit 0753-1599

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) researcher Meagan Jones recording identification data, Maui, Hawaii

Flip Nicklin / Sperm Whale (Physeter macrocephalus) researcher, Hal Whitehead, listening for whales on hydrophone, Sri Lanka

Flip Nicklin / Sperm Whale (Physeter macrocephalus) researcher, Phil Gillian, listening for whales on hydrophone about Hal Whitehead's boat, Balaena, Sri Lanka

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) researcher Dr James Darling listening to whales, Hawaii

Flip Nicklin / Inuit researcher using hydrophone to record Narwhal (Monodon monoceros) vocalizations under the arctic ice, Baffin Island, Canada

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) songs being recorded by Dr James Darling and research assistant, Maui, Hawaii

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) singer approaches hydrophone hanging from research boat, Maui, Hawaii - notice must accompany publication; photo obtained under NMFS permit 987

Flip Nicklin / Humpback Whale (Megaptera novaeangliae) researcher Dr James Darling listening to singing whales, Maui, Hawaii

Flip Nicklin / Dwarf Minke Whale (Balaenoptera acutorostrata) researcher Jason Gedamke using hydrophone to track whales, Australia