the Editor: Without the aid of diving equipment, humans can only descend to a limited depth. But did you know? There is a group of creatures that have spent tens of millions of years evolving to thrive in the deep sea — beaked whales. These mysterious cetaceans occasionally appear in Taiwan's eastern waters, and among them, Cuvier's beaked whale uses its remarkable physiology to dive to depths of nearly 3,000 meters. In recent years, however, deep-sea exploration and human activities have posed growing threats to cetaceans. This article lifts the veil on the enigmatic beaked whale. Reproduced in full from the Kuroshio Ocean Education Foundation.
Figure 1. A chance encounter with a ginkgo-toothed beaked whale during a marine oasis habitat-use survey
Some have described the ocean as "Inner Space," because the sea, much like outer space, is filled with the unknown. For centuries, the ocean has carried countless secrets beyond human reach. Due to the limited pressure tolerance of the human body, we can only dive to depths of a little over one hundred meters without the assistance of a submersible. The ocean's vast expanse, ever-changing sea conditions, and the utter darkness of the deep have kept us from fully exploring marine ecosystems — even in an age of rapidly advancing technology.
Figure 2. A styrofoam cup crushed by deep-sea pressure to the size of a shot cup (courtesy of M. Grady.)
Yet in the vast open ocean, there exists a remarkable group of oddballs that have spent tens of millions of years evolving to comfortably enter and exit the deep sea — the beaked whales (Family: Ziphiidae). Their elusive behavior makes them nearly impossible to track, but the dramatic underwater topography off Taiwan's eastern coast — with steep continental slopes that plunge like a slide into the abyss — means that even a whale-watching trip of just an hour or two can bring vessels over waters thousands of meters deep, giving us a rare opportunity to glimpse these mysterious cetaceans.
Beaked whales get their name from their prominent, beak-like snouts. They have relatively small dorsal fins and slender bodies ranging from about 4 to 13 meters in length. They are notoriously difficult to approach and are masterful deep divers. According to current research records, Cuvier's beaked whale (Ziphius cavirostris) — a member of the beaked whale family — can dive to depths of nearly 3,000 meters and hold its breath for up to approximately 3 hours. Capable of remaining submerged for extraordinary lengths of time and withstanding pressures hundreds of times greater than at the surface, it holds the record for the deepest and longest dive of any species. Cetacean bodies function like oxygen reservoirs, containing large quantities of blood and myoglobin¹, which allows them to remain active underwater for extended periods. During a dive, they also slow their heart rate to reduce oxygen consumption, further extending their breath-hold time.
Figure 3. A rare visitor to the waters off Hualien — Cuvier's beaked whale
Which Species of Beaked Whale Have Been Recorded in Taiwan?
"Beaked whales! Don't miss them — they'll be gone in a flash!" As camera resolution improves and burst-shooting speeds increase, identifying beaked whale features through photographic evidence has become ever more precise. Based on past stranding and at-sea sighting records in Taiwan, the species documented to date include Cuvier's beaked whale, the ginkgo-toothed beaked whale (Mesoplodon ginkgodens), Blainville's beaked whale (Mesoplodon densirostris), and the Longman's beaked whale (Indopacetus pacificus)². The Kuroshio Foundation's currently available sighting data also includes records of ginkgo-toothed beaked whales and Cuvier's beaked whales (Figure 3), with Cuvier's beaked whale being the most frequently encountered; ginkgo-toothed beaked whale sightings number fewer than ten records over the years.
Figure 4. When beaked whales are encountered, researchers must quickly assess the cetacean's position and direction of travel, and use a telephoto lens to capture head features
Beaked whale sightings in Hualien waters are extremely rare — over more than 20 years of data collection, only around 80 records have been accumulated, representing less than 1% of all cetacean sightings. This underscores just how difficult it is to spot them in the wild. Members of the beaked whale family are notoriously hard to approach, and the time they spend at the surface is extremely brief — typically only tens of seconds to a minute or two before they dive back into the deep. For this reason, whenever a beaked whale is spotted during a survey, the first order of business is to ask researchers to raise their cameras and focus on photographing the head of an adult male, as this yields the most diagnostic identifying features. Based on Kuroshio's cetacean sighting location data (Figure 5), beaked whales tend to appear in more offshore areas, primarily in waters more than 5 kilometers from the coast. This may be related to the distribution of their primary prey — cephalopods. Some records are logged only at the family level (Ziphiidae) because there was insufficient photographic evidence to determine the species.
Figure 5. Beaked whale sighting locations off Hualien, 1998–2023
A Warning from the Deep — What Beaked Whales Tell Us
Figure 6. Large quantities of plastic products found in the stomach of a stranded Cuvier's beaked whale in 2019 (Photo credit: Ocean Conservation Administration)
On March 16, 2019, a dead, pregnant Cuvier's beaked whale was discovered on a Hualien beach. In addition to food remains, its stomach contained a large amount of human-made waste, including burlap sacks and numerous plastic products. This stranding event made clear that even though beaked whales inhabit the deep sea — a world that seems entirely separate from our own — single-use items, fishing-related waste, and even military activities can all have significant impacts on these animals. For example, an anomalous mass stranding of beaked whales and other deep-sea species across Taiwan in 2005 may also have been linked to noise from naval exercises in nearby waters.
Figure 7. Deep-sea exploration equipment (The Metals Company)
Deep-sea mining is another major cause for concern. China is a key exporter of rare earth elements³, and Japan — long reliant on Chinese rare earths — has in recent years begun investing heavily in deep-sea exploration to boost its own production capacity, identifying several areas with potential for extraction in preparation for future hybrid and electric vehicle manufacturing. Currently, baseline data on deep-sea species is severely lacking, and the powerful acoustic signals used in exploration, along with the machinery involved in excavation, could pose unknown threats from human activity. As deep-sea exploration expands, these risks may worsen further. For this reason, in the second phase of the Marine Oasis project, we aim to make active use of Hualien's environmental and geographic advantages to gather baseline data that can serve as a reference for future marine protected area designation and conservation efforts. We also encourage readers to follow the Marine Oasis deep-sea species survey project and stay informed on related developments. If you have any beaked whale sighting records, please feel free to contact us at kuroshio@koef.org.
References
- Mead, J. G. (2009). Beaked Whales, overview. In Elsevier eBooks (pp. 94–97). https://doi.org/10.1016/b978-0-12-373553-9.00027-4
- Yang, W., Ls, C., Jepson, P., Brownell, R., Cowan, D. F., Ph, C., Hi, C., Cj, Y., Tk, Y., Jt, C., Pj, W., & Fernández, A. (2008). Unusual cetacean mortality event in Taiwan, possibly linked to naval activities. Veterinary Record, 162(6), 184–185. https://doi.org/10.1136/vr.162.6.184
- Cuvier's Beaked Whale | NOAA Fisheries
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- Japan to begin extracting rare earth metals from seabed in 2024 - Nikkei Asia
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- 全文轉載自：一瞥來自於內太空的神秘客——喙鯨
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