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What the sources say

Harbor SealPhoca vitulina

Every figure, record and mechanism on the Harbor Seal profile was written from a source, and this is the working table behind it: 40 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

NOAA Fisheries

Harbor Seal. NOAA Fisheries.

The page saysalong the northern coasts of North America, Europe and Asia
The source saysHarbor seals live in temperate coastal habitats along the northern coasts of North America, Europe, and Asia
The page sayshauling out on rocks, beaches and drifting glacial ice
The source saysHarbor seals haul out (rest) on rocks, reefs, beaches, and drifting glacial iceNote: reefs dropped from the source's list
The page saysin North America from Baja California to the Bering Sea and from the Canadian Arctic to the Mid-Atlantic
The source saysharbor seals are found from the Canadian Arctic to the Mid-Atlantic ... all along the West Coast of North America, from Baja California, Mexico to the Bering SeaNote: quote spans two sentences of the same paragraph; NOAA gives the Atlantic-coast range first, then the Pacific-coast range
The page saysThe harbor seal (Phoca vitulina) is a true seal.
The source saysHarbor seals are part of the true seal family.
The page saysIt has no external ear flaps, just a small hole on each side of its head
The source saysThey also lack external ear flaps and instead have a small hole (opening to the ear canal) on either side of their head.
The page saysits pelvic bones are fused, so it can't tuck its hind flippers under its body to walk the way a sea lion does. On land it gets around by undulating like a caterpillar instead
The source saysHarbor seal pelvic bones are fused, preventing them from moving their hind flippers under their pelvis to walk on land like sea lions. Instead, they move by undulating in a caterpillar-like motion.Note: 'so' paraphrases the source's own 'preventing'
The page saysA harbor seal weighs up to 285 pounds and measures up to 6 feet long
The source saysHarbor seals weigh up to 285 pounds and measure up to 6 feet in length.Note: NOAA's page (last updated 03/25/2026) replaces the Smithsonian's 120-300 lb male range, which it contradicts
The page saysmales are slightly larger than females, and seals in Alaska and the Pacific are generally larger than those in the Atlantic
The source saysMales are slightly larger than females, and seals in Alaska and the Pacific Ocean are generally larger than those found in the Atlantic Ocean.
The page saysalong North America's west coast from Baja California to the Bering Sea, its east coast from the Canadian Arctic to the Mid-Atlantic, and the northern coasts of Europe and Asia
The source saysHarbor seals live in temperate coastal habitats along the northern coasts of North America, Europe, and Asia ... On the eastern North America Coast, harbor seals are found from the Canadian Arctic to the Mid-Atlantic. Harbor seals are found all along the West Coast of North America, from Baja California, Mexico to the Bering Sea.
The page saysIt's ready to swim within minutes of birth, can dive for up to 2 minutes by the time it's 2 or 3 days old, and by the end of its first month may set off on journeys of more than 100 miles from its birth site
The source saysHarbor seal pups can swim at birth. They can also dive for up to 2 minutes when they are only 2 to 3 days old and by the end of their first month of life embark on journeys of over 100 miles from their natal area. ... Pups weigh about 24 pounds at birth and are ready to swim within minutes.
The page saysIt nurses for 4 to 6 weeks on milk that's 50 percent fat
The source saysThey nurse for 4 to 6 weeks on milk that is 50 percent fat.
The page saysseals that haul out in groups spend less time watching for predators than those that haul out alone
The source saysThese seals also haul out in groups to avoid predators and spend less time being watchful for predators than those that haul out alone.
The page saysYes. Harbor seal pups can swim at birth. By 2 to 3 days old they can dive for up to 2 minutes, and by the end of their first month they may set off on journeys of more than 100 miles from where they were born. They nurse for 4 to 6 weeks on milk that's 50 percent fat
The source saysHarbor seal pups can swim at birth. They can also dive for up to 2 minutes when they are only 2 to 3 days old and by the end of their first month of life embark on journeys of over 100 miles from their natal area. ... They nurse for 4 to 6 weeks on milk that is 50 percent fat.

Source
02

Smithsonian's National Zoo and Conservation Biology Institute

Harbor seal. Smithsonian's National Zoo and Conservation Biology Institute.

The page saysa diver whose heart can slow to three or four beats a minute
The source saysBefore a deep dive, harbor seals exhale to reduce the amount of oxygen in their lungs, relying instead on stored oxygen in their blood and muscle tissues. ... Harbor seals also slow their heart rates from upwards of 80-120 beats per minute to as few as three or four.Note: vibe.reason, settled after the wave: the heart-rate sentence sits in the Smithsonian's diving paragraph
The page saysa heart rate that can drop to three or four beats a minute on a dive
The source saysLike other pinnipeds, harbor seals are adapted to dive and conserve oxygen underwater. ... harbor seals also slow their heart rates from upwards of 80-120 beats per minute to as few as three or fourNote: the heart-rate sentence sits in the Smithsonian's paragraph on diving, after 'Before a deep dive'
The page saysthe widest range of any seal on Earth
The source saysThey have the widest distribution of any seal
The page saysRockfish, herring, cod, mackerel, flounder and salmon, plus squid, octopus, crabs and shrimp
The source saysprimarily eat fish, such as rockfish, herring, cod, mackerel, flounder and salmon. They also eat squid, clams, octopus, crayfish, crabs and shrimp when available.Note: clams and crayfish dropped from the stats field's list for brevity; all listed items are verbatim from the source
The page saysIt has the widest range of any seal
The source saysThey have the widest distribution of any seal
The page saysA wild harbor seal can live 25 to 30 years, and more than 30 in human care
The source saysHarbor seals in the wild can live between 25 and 30 years and for more than 30 years in human care.Note: NOAA's 2026 page agrees (Lifespan About 25 to 30 years); ADW's 2012 account (average 40 years wild) is overruled
The page saysA harbor seal eats mainly fish, such as rockfish, herring, cod, mackerel, flounder and salmon, plus squid, octopus, crabs and shrimp when available
The source saysprimarily eat fish, such as rockfish, herring, cod, mackerel, flounder and salmon. They also eat squid, clams, octopus, crayfish, crabs and shrimp when available.Note: clams and crayfish dropped from the source's list
The page saysBefore a deep dive, a harbor seal exhales to cut the oxygen in its lungs and relies on oxygen stored in its blood and muscle instead
The source saysBefore a deep dive, harbor seals exhale to reduce the amount of oxygen in their lungs, relying instead on stored oxygen in their blood and muscle tissues.
The page saysBlood is shunted away from its extremities toward its brain, heart and lungs, and its heart rate slows from upwards of 80 to 120 beats a minute to as few as three or four
The source saysBlood is shunted away from the extremities and concentrated on maintaining the core functions of the brain, heart and lungs where it is needed. Harbor seals also slow their heart rates from upwards of 80-120 beats per minute to as few as three or four.
The page saysIt can stay under for up to 30 minutes, though the average dive lasts under three
The source saysThey can remain submerged for up to 30 minutes at a time, but the average dive lasts less than three minutes
The page saysIt can generally dive to about 500 feet, but dives as deep as 1,460 feet have been recorded
The source saysThey can generally dive to depths of about 500 feet (152 meters), but dives up to 1,460 feet (446 meters) have been recorded.Note: ADW's 2012 maximum of 427 m is older and smaller; the Smithsonian's recorded 446 m stands
The page saysIts body burns energy faster than other mammals its size, which generates heat to keep it warm, and in winter its insulating blubber can make up as much as 30 percent of its body mass
The source saysThese seals have a higher metabolic rate than other mammals of comparable size, which allows them to generate heat to keep warm ... A thick layer of insulating blubber provides thermoregulation and a nutrient reserve for fasting periods. During the winter, the blubber layer can account for up to 30 percent of a harbor seal's body mass.Note: 'burns energy faster' renders 'higher metabolic rate' for readers aged 11 to 14
The page saysHarbor seals stay alert for predators such as polar bears, orcas and sharks
The source saysHarbor seals spend the majority of their time staying alert for predators, such as polar bears, orcas and sharks.
The page saysA seal that senses danger gives an alarm call and usually dives for the water
The source saysit will let out an alarm call and flee, usually by diving into the water, if it senses danger
The page saysBefore a deep dive it exhales to cut the oxygen in its lungs, relying instead on oxygen stored in its blood and muscle. Blood is shunted away from its extremities toward its brain, heart and lungs, and its heart rate slows from upwards of 80 to 120 beats a minute to as few as three or four, then speeds up rapidly for a short time after it surfaces. It can stay down for up to 30 minutes, though the average dive lasts under three
The source saysThey can remain submerged for up to 30 minutes at a time, but the average dive lasts less than three minutes ... Before a deep dive, harbor seals exhale to reduce the amount of oxygen in their lungs, relying instead on stored oxygen in their blood and muscle tissues. Blood is shunted away from the extremities and concentrated on maintaining the core functions of the brain, heart and lungs where it is needed. Harbor seals also slow their heart rates from upwards of 80-120 beats per minute to as few as three or four. After surfacing, the seal's heartbeat accelerates rapidly for a short period of time.
The page saysYes. Harbor seals have the widest distribution of any seal, living in both the North Atlantic and North Pacific oceans, from cool temperate waters up into cold Arctic and sub-Arctic coasts
The source saysThey have the widest distribution of any seal and live in both the North Atlantic and Northern Pacific oceans, ranging from cool, temperate waters to cold, arctic and sub-arctic coasts.

Source
03

Animal Diversity Web, University of Michigan

Phoca vitulina (harbor seal). Animal Diversity Web, University of Michigan.

The page saysCoastal bays and estuaries
The source saysHarbor seals populate the shallow waters of coastal areas, bays, rocky islets, estuaries, and even freshwater lakes.
The page saysaiming to keep its foraging effort low by eating what is abundant and easily caught
The source saysthe overarching goal of harbor seals is to keep foraging efforts low by eating what is abundant and easily caught
The page saysA harbor seal pup sheds its downy lanugo coat well before birth and is born with fur the same texture as an adult's, which lets it safely enter cooler water
The source saysa fine, downy coat of hair called lanugo after birth, harbor seal pups shed their lanugo well before they are born. At birth, the pups' fur is the same texture as that of the adults, which allows them to safely enter cooler waters.Note: 'which lets' paraphrases the source's 'which allows'

Source
04

Dehnhardt et al. 2001

Dehnhardt et al. (2001). Hydrodynamic Trail-Following in Harbor Seals ( Phoca vitulina ). Science.

The page saysWhiskers that detect a swimming fish's wake
The source saysfish-generated water movements, which seals can detect with their highly sensitive whiskers. Water movements in the wake of fishes persist for several minutes.
The page saysHighly sensitive whiskers that detect the water movements a swimming fish leaves behind; blindfolded seals can use them to accurately follow a hydrodynamic trail
The source saysfish-generated water movements, which seals can detect with their highly sensitive whiskers. ... blindfolded seals can use their whiskers to detect and accurately follow hydrodynamic trails generated by a miniature submarineNote: the trail the blindfolded seals followed was a miniature submarine's, so the page does not say they followed a fish's
The page saysIn dark or murky water, dolphins hunt using echolocation
The source saysMarine mammals often forage in dark or turbid waters. Whereas dolphins use echolocation under such conditionsNote: final pass: 'often' belongs to marine mammals foraging in dark water, not to dolphins, so it is dropped
The page saysSeals apparently don't have that sense
The source sayspinnipeds apparently lack this sensory abilityNote: paraphrase of 'lack this sensory ability' as 'don't have that sense'; 'Seals' narrows the abstract's 'pinnipeds', a term the page never defines
The page saysa seal's highly sensitive whiskers can detect the water movements a fish makes, and those movements persist in its wake for several minutes
The source saysfish-generated water movements, which seals can detect with their highly sensitive whiskers. Water movements in the wake of fishes persist for several minutes.
The page saysResearchers once blindfolded harbor seals and had them track the wake of a miniature submarine with their whiskers; the seals followed it accurately, showing that water movements like these can be used to locate prey at long distance
The source saysblindfolded seals can use their whiskers to detect and accurately follow hydrodynamic trails generated by a miniature submarine. This shows that hydrodynamic information can be used for long-distance prey location.Note: the paper's title names the species: Hydrodynamic Trail-Following in Harbor Seals (Phoca vitulina); 'water movements like these' renders 'hydrodynamic information' for readers aged 11 to 14
The page saysSeals apparently lack the echolocation dolphins use in dark or murky water. Instead, a harbor seal's highly sensitive whiskers can detect the water movements a swimming fish makes, which persist in its wake for several minutes. In one study, blindfolded seals used their whiskers to detect and accurately follow the wake of a miniature submarine, showing that water movements like these can be used to locate prey at long distance
The source saysMarine mammals often forage in dark or turbid waters. Whereas dolphins use echolocation under such conditions, pinnipeds apparently lack this sensory ability. For seals hunting in the dark, one source of sensory information may consist of fish-generated water movements, which seals can detect with their highly sensitive whiskers. Water movements in the wake of fishes persist for several minutes. Here we show that blindfolded seals can use their whiskers to detect and accurately follow hydrodynamic trails generated by a miniature submarine. This shows that hydrodynamic information can be used for long-distance prey location.Note: 'Seals' narrows the abstract's 'pinnipeds'

Source
05

Russell 2025

Russell (2025). Phoca vitulina. The IUCN Red List of Threatened Species 2025: e.T17013A225215605.

The page saysThe IUCN lists the harbor seal as Least Concern
The source saysIUCN Red List category: Least Concern (LC).

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.