It opens its enormous mouth, filtering microscopic plankton like an oceanic harvester, sustaining its massive frame in the most tranquil manner.
In the vast oceans, inhabits the second-largest fish species—the basking shark. This colossal creature, reaching up to 12 meters in length, possesses an extremely gentle filter-feeding behavior. They swim slowly near the water's surface with their nearly 1-meter-wide mouths agape, filtering plankton from the water like gentle giants of the sea1 .
Despite their impressive size, basking sharks pose no threat to humans. However, their slow swimming speed and gentle disposition have made them vulnerable to extinction1 .
Maximum recorded length
Weight of largest specimen
Water filtering capacity
The basking shark (Cetorhinus maximus) is a highly unique species within the order Lamniformes. It is the only species within both the family Cetorhinidae and genus Cetorhinus, making it a living fossil in evolutionary history1 .
This shark species has a wide distribution, found throughout temperate oceans worldwide. From Newfoundland to Florida in North America, and from Japan and China to Australia and New Zealand waters, their presence may be detected5 .
| Feature Category | Description |
|---|---|
| Taxonomic Position | Only species in family Cetorhinidae and genus Cetorhinus1 |
| Global Distribution | Temperate oceans worldwide1 |
| Largest Recorded Individual | 12.27 meters, 19 tons1 |
| Common Length | 6-10 meters1 |
| Unique Anatomical Features | Nearly head-encircling gill slits, hook-shaped small teeth, enormous liver constituting 25% of body weight1 |
| Feeding Method | Active swimming filter-feeding, capable of filtering 2000 tons of water per hour1 |
| Conservation Status | IUCN Endangered species, China's National Class II protected animal1 5 |
Size comparison of basking shark with other marine creatures and human
Despite their slow swimming speed of approximately 4 km/h, basking sharks can perform a remarkable action—completely leaping out of the water1 7 . This spectacular behavior has long puzzled scientists.
For such an enormous creature, breaching requires significant energy expenditure, raising the key question: Why do basking sharks engage in such high-energy activities?
Recent research indicates that breaching behavior in sharks and rays is not due to a single cause but involves multiple complex ecological functions, including removal of external parasites, foraging, courtship, and as a form of communication2 .
For basking sharks, parasite removal may be a particularly important motivation5 .
Research in the Northeast Atlantic provided strong evidence for this hypothesis. Scientists collected 775 basking shark records between 2011-2020, including videos, photographs, and written observations3 .
After rigorous quality control, they analyzed 434 records and found that 41.8% of basking sharks had lampreys attached, with an average of 1.9 lampreys per shark, and one individual hosting up to 8 parasites3 .
Lampreys are ancient parasitic creatures that attach to host skin, feeding on blood and tissue fluids. While unlikely to penetrate the basking shark's thick skin, their presence clearly causes discomfort and energy drain3 5 .
Breaching and slamming back into the water may be an effective de-parasiting mechanism, using the tremendous impact force to dislodge these unwelcome guests.
Percentage of basking sharks with attached lampreys based on research observations
To gain deeper insights into basking shark movement ecology, particularly their annual activity patterns in high-latitude regions, a research team conducted a groundbreaking tracking study in northern Norway6 .
Researchers equipped three basking sharks with pop-up satellite archival tags (PSATs). These high-tech devices recorded depth, water temperature, light levels, and acceleration data with a sampling interval of just 5 seconds, providing unprecedented high-resolution data6 .
| Research Element | Implementation Method |
|---|---|
| Study Location | Northern Norway (Lofoten and Vesterålen islands, approx. 68°N)6 |
| Study Subjects | 3 basking sharks (sex determined via underwater video)6 |
| Tracking Technology | Pop-up satellite archival tags (PSATs)6 |
| Data Recording | Depth, water temperature, light, tri-axial acceleration, 5-second intervals6 |
| Tracking Duration | Programmed for 365 days6 |
| Data Retrieval | Tags recovered at sea using Argos direction finder6 |
| Data Analysis | Statistical analysis and visualization using R6 |
The study results were remarkable. Two tracked female basking sharks exhibited distinctly different migration strategies6 .
Temperature ranges encountered by tracked basking sharks
| Environment Type | Vertical Movement Pattern | Presumed Ecological Drivers |
|---|---|---|
| Oceanic Habitats | Greater use of mid-water depths, normal diel vertical migration (ascent at dusk, descent at dawn)6 | Following plankton's light-avoidance behavior6 |
| Continental Shelf Regions | Depth use constrained by topography, more variable patterns6 | Dynamic hydrological conditions and prey distribution6 |
| Inner Shelf Areas | Vertical behaviors with tidal rhythms6 | Tide-induced vertical displacement of plankton6 |
| Winter Period | Diving to deeper waters (approx. 900 meters)1 | Following deep plankton layers1 |
The recorded eurythermy and behavioral plasticity indicate that basking sharks are highly adapted to dynamic ocean conditions. These characteristics are crucial for responding to rapid climate changes in abiotic and biotic environments at high latitudes6 .
Modern basking shark research relies on a combination of high-tech tools and traditional methods. These technologies enable scientists to unravel the life mysteries of this enigmatic giant.
Pop-up satellite archival tags (PSATs) are core tools for studying basking shark migration. Attached near the shark's dorsal fin, these tags record depth, temperature, light, and acceleration data6 .
Each basking shark's dorsal fin shape and skin patterns are unique, like fingerprints. Researchers photograph sharks to establish "shark passport" identification systems4 .
Using non-invasive methods to collect eDNA samples and skin tissue, researchers analyze kinship relationships between different basking shark populations4 .
Since basking sharks feed on plankton, scientists collect plankton samples in feeding and non-feeding areas to analyze density and composition4 .
Research expeditions engage citizen scientists to record basking shark locations, timing, size, sex, and behavior while collecting environmental data4 .
Advanced statistical methods and visualization techniques using R and other analytical tools help interpret complex tracking and observation data6 .
| Research Technology & Tools | Function & Application | Scientific Questions Addressed |
|---|---|---|
| Satellite Tracking Tags (PSATs) | Record depth, temperature, light, acceleration; track migration6 | Annual movement patterns, habitat selection, environmental tolerance6 |
| Photo Identification | Use unique dorsal fin and skin patterns for individual identification4 | Population numbers, short-term movements, site fidelity4 |
| Genetic Sampling | Non-invasive collection of eDNA and skin samples4 | Population genetic structure, kinship relationships, migration pathways4 |
| Plankton Sampling | Analyze plankton composition and microplastic pollution4 | Feeding ecology, environmental pollution exposure risks4 |
| Citizen Science Observations | Systematic recording of basking shark sightings and environmental data4 | Population distribution, abundance trends, behavioral patterns4 |
Effectiveness ratings of different research methods for studying basking sharks
The recorded eurythermy and behavioral plasticity indicate that basking sharks are highly adapted to dynamic ocean conditions. These characteristics may be crucial for responding to rapid climate changes in abiotic and biotic environments at high latitudes6 .
However, despite these impressive adaptations, basking sharks face extinction risks due to extremely low reproductive rates and human overexploitation1 .
Due to their slow swimming, gentle nature, and formerly abundant numbers, basking sharks became prime fishery targets, used for shark fin, meat, liver oil, and various commercial purposes1 .
Today, basking sharks are protected in many countries with restricted trade, including the UK, Malta, parts of the USA, and New Zealand, all implementing relevant conservation regulations1 .
In-depth research on basking sharks not only enriches our understanding of marine ecosystems but also provides scientific basis for protecting these gentle giants. With events like the 2025 International Basking Shark Conference, global scientists are strengthening cooperation to collectively safeguard the future of these oceanic filter-feeding giants8 .