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288 Marine Mammals of the World

Lobodon carcinophagus (Hombron and Jacquinot, 1842) PHOC Lob 1 SET

FAO Names: En - Crabeater seal; Fr - Phoque crabier; Sp - Foca cangrejera.

Fig. 565 Lobodon carcinophagus

Distinctive Characteristics: In Crabeater seals,

the head and muzzle are moderately long and thin
relative to the animal’s overall size. The eyes are
set fairly far apart and the head tapers to the base
of the straight muzzle, forming a slight forehead in
profile. The nostrils are on top of the muzzle, just
back from the end. The line of the mouth is virtu-
ally straight. The vibrissae are short, pale to clear,
and inconspicuous. The foreflippers are long, oar
shaped, and pointed, like those of otariids. The
first digits are elongated and robust, and the fifth
digit is reduced. Many crabeaters bear long dark DORSAL VIEW WITH MANDIBLE
scars, either singly or as a parallel pair, attributable
to attacks by leopard seals.
The coat of a freshly moulted crabeater has a rich
sheen, with light to dark tones of silvery grey to
yellowish brown. There are irregular patches of
spots and rings, often in clusters on the sides,
flippers, and around the insertions of the flippers.
These markings produce a reticulated, or web-
like, pattern on many crabeaters. The flippers can
be so heavily marked with spots and rings that they
appear darker than the rest of the body. As the
year progresses, crabeaters fade dramatically, vir- VENTRAL VIEW WITH MANDIBLE
tually eliminating the contrast between top and
bottom. As these seals become older they be-
come paler overall, and some look faded all year.
Pups are born with a soft woolly coat that is greyish
brown, with darker colouring on the flippers. Moult
begins in about 2 to 3 weeks and the pup sheds
into a subadult pelage similar to that of the adult.
Most crabeaters have at least a few and often
many long scars on the body, which are most often
seen in pairs, parallel or near to each other. These LATERAL VIEW WITH MANDIBLE
scars are thought to be the result of unsuccessful
leopard seal attacks on the seals as juveniles. Fig. 566 Skull
Carnivora - Pinnipedia - Phocidae 289

Additionally many older animals are extensively scarred on the neck, face, and around the lower jaws.
All of the post-canine teeth are ornate, with multiple accessory cusps. Upper and lower teeth interlock to
form a network for straining krill from the water. The dental formula is I 2/2, C 1/1, PC 5/5.
Can be confused with: Crabeater seals are most likely to be confused with leopard (p. 292) and Weddell
(p. 294) seals. The former has a massive reptilean head, long foreflippers, and huge maw. The latter has
a very small head, relative to the rotund body, and a distinctly spotted coat. Only crabeaters occur routinely
in large groups.
Size: Adults reach 2.6 m in length and, although little data is available, weigh an estimated 200 to 300 kg.
Neonates are thought to be at least 1.1 m and 20 to 40 kg.
Geographical Distribution: The distribution of crabeater seals is tied to the seasonal fluctuations of the
pack ice. They can be found right up to the coast of Antarctica, as far south as McMurdo Sound, during late
summer ice break-up, and as vagrants as far north as New Zealand and the lower reaches of Africa, Australia,
and South America.

Areas of extralimital records

Fig. 567

Biology and Behaviour: Pups are born from September to December, and mating most likely occurs from
October through December (although little is known about their reproduction). There are no specific
rookeries: females haul out on ice, give birth, and aggressively ward off other seals, particularly males.
Crabeaters are frequently encountered alone or in small groups of up to 10 on the ice or in the water.
However, much larger groups of up to several thousands have been observed. Occasionally, they can be
seen traveling together in herds, breathing and diving almost synchronously. They are known for their ability
to move rapidly on ice, with sinuous serpentine motions of the back, aided by the flippers, When agitated,
their response is to arch their back and raise their neck and head, and often point the nose upwards at a
slight angle in an alert posture.
Recent research has revealed that crabeater seals can dive to 430 m and for 11 minutes, although most
feeding dives were much shallower and shorter. It is believed that crabeaters feed with greatest intensity at
night, mostly on krill.
Exploitation: Crabeater seals have never been seriously exploited by humans. They continue to be taken
for scientific research and to feed sled dogs kept at Antarctic bases. They are probably the most numerous
pinniped, and may be the most numerous large mammal on earth besides humans. It has been speculated
that the population of crabeater seals is at an all time high due to the demise of the large stocks of krill-eating
baleen whales.
IUCN Status: Insufficiently known.
290 Marine Mammals of the World

Ommatophoca rossii (Gray, 1844) PHOC Omn 1 SRS

FAO Names: En - Ross seal; Fr - Phoque de Ross: Sp - Foca de Ross.

Fig. 568 Omtnatophoca rossii

Distinctive Characteristics: Ross seals are

poorly known. They are the smallest of the Antarc-
tic phocids. The head is relatively wide and short.
The muzzle is likewise short, wide, and comes to
a blunt end. The small number of short, slender
vibrissae are possibly the shortest of any pinniped.
The eyes are set widely apart and are average in
size, despite the huge orbits in the skull. The throat
and neck are quite thick, but the rest of the body is
of average build for a phocid. The coat is the
shortest of any phocid. The hindflippers are very
long, just over one-fifth of the standard length. DORSAL VIEW

Ross seals are typically countershaded, dark grey

above, blending along the sides, and becoming
silvery below. Most striking are the beautiful brown
to reddish brown streaks, unique to this pinniped,
extending parallel to the long axis along the neck,
chest, and sides. The face may appear masked as
a result of the merging of streaks at the eyes and
on the lower jaw. There may also be spots, par-
ticularly on the sides. Ross seals may have some-
thing like an epidermal moult that involves
shedding small pieces of skin. Small scars are VENTRAL VIEW
often seen on the neck, possibly from intraspecific
fighting, and some adults bear larger scars, prob-
ably from leopard seal or killer whale attacks.
The dental formula is I 2/2, C 1/1, PC 5/5.

LATERAL VIEW
WITH MANDIBLE

Fig. 569 Skull

Carnivora - Pinnipedia - Phocidae 291

Can be confused with: Of the 4 other phocids that share the Ross seal’s range (Weddell (p. 294), crabeater
(p. 288), leopard (p. 292), and southern elephant (p. 286) seals), the Weddell is most similar in appearance.
However, Ross seals are much smaller and have a wider head, and relatively thicker neck (with streaks).
Ross seals also’tend to be found deeper into the thick pack ice than any other Antarctic phocid.
Size: Based on a small sample of measured animals, Ross seals reach at least 2.4 m and 204 kg. Females
are slighlty larger than males. It is estimated that newborn pups are about 1 m and 16 kg.
Geographical Distribution: Ross seals have a circumpolar distribution in the Antarctic. They are usually
found in dense consolidated pack ice, but can also be found on smooth ice floes in more open areas.

m Area of extralimital records * Extralimital record

Fig. 570

Biology and Behaviour: Breeding is thought to occur from November through December. When hauled-
out, Ross seals are generally encountered alone. Occasionally, a small number of individuals may be found
in the same area, but they are usually widely spaced. They may haul out more from morning to late afternoon.
However, during the period of the moult, they may be out of the water for longer periods.
Few behaviours have been noted, except for the interesting habit of raising up the head and neck when
approached by a human. The seal either stays on its belly or rolls onto its side, keeping the belly towards
the person. In this “singing” posture, it opens the mouth to produce trilling, siren-like calls, or chugging
vocalizations.
Little is known of the activities of Ross seals in the water, although recent work has revealed that dives
average 100 m and 6 minutes. The diet of Ross seals consists primarily of cephalopods, but also includes
fishes and krill in some areas.
Exploitation: Ross seals have never been the target of anything but small scale and incidental sealing.
Very few have ever been taken for research, and they are poorly represented in scientific collections. This
is arguably the most inaccessible seal to humans, and explains the limited exploitation and paucity of
knowledge available.
IUCN Status: Insufficiently known.
292 Marine Mammals of the World

Hydrurga leptonyx (Blainville, 1820) PHOC Hydr 1 SLP

FAO Names: En - Leopard seal; Fr - Leopard de mer; Sp - Foca leopardo.

Fig. 572 Hydrurga leptonyx

Distinctive Characteristics: Leopard seals have

a sinuous body and massive head and jaws. Be-
cause of the shape of the head, they appear
almost reptilian. Females grow slightly longer and
heavier, but not enough to allow the sexes to be
distinguished in the field based on size. The long
body is thin overall, thickest through the shoulders
and upper chest. There is no trace of a forehead.
The head is widest at the eyes, which appear small
and set both far apart and well back from the end
of the muzzle. The nostrils are on top of the
muzzle, just back from the wide rounded end. The DORSAL VIEW WITH MANDIBLE
lower jaw is massive, wide, and deep, as are the
throat and neck. The vibrissae are clear to pale,
generally quite short and inconspicuous. Leopard
seals have an enormous gape. The very long
(almost one-third of the body length) foreflippers
are broad and otariid-like. They are completely
furred and each digit bears a short terminal claw.
The first digit is long and massive, creating a thick
strong leading edge.
Leopard seals are basically countershaded. The
darker top is silver to dark grey, and it blends along VENTRAL VIEW WITH MANDIBLE
the midsides and neck at about the level of the
eyes with the paler undersides, which are light
grey. There is a swath of lighter colour on the upper
lip. Leopard seals are spotted to varying degrees,
usually most noticeably on the sides and belly.
Pups have essentially the same markings and
proportions as adults, although their coat is softer,
longer, and thicker. Dense constellations of spots
may occur without any pattern or symmetry. One
area where dense clusters of spots normally oc-
curs is around the insertions of the foreflippers. LATERAL VIEW WITH MANDIBLE

Fig. 571 Skull

Carnivora - Pinnipedia - Phocidae 293

The dental formula is l 12/2, C 1/1, PC 5/5 The canine teeth are very long (up to 2.5 cm) and sharply pointed.
The remaining teeth are complex and multi-lobed, somewhat resembling those of crabeaters.
Can be confused with: When seen well, leopard seals are unmistakable. At a distance, however, they
might be confused with crabeater (p. 288) or Weddell (p. 294) seals. Of these, the crabeater is the most
likely candidate for confusion.To rule out other species, note the size and shape of the head, overall
coloration, and length of the foreflippers.
Size: Adults usually reach 3 m and weigh 270 to 450 kg. Very large females may reach 3.6 m and 500 kg.
Pups are born at about 1 to 1.6 m and around 30 to 35 kg.
Geographical Distribution:Leopard seals are widely distributed in the polar and subpolar waters of the
Southern Hemisphere, from Antarctica north, and regularly reach warm temperate latitudes as vagrants.
They are found throughout the pack ice zone, where their abundance is greatest. They haul-out on ice and
land, often preferring ice floes, when available.

Areas of extralimital records

Fig. 573

Biology and Behaviour: Little is known of breeding behaviour. Pups are born on the ice from September
to January, with a peak in November to December.
At sea and on the ice, leopard seals tend to be solitary. They float at the surface, and crane their neck high
to view objects of interest. Sounding in this species is commenced either by sinking or rolling forward.
Swimming is most often accomplished with long, powerful, coordinated sweeps of the foreflippers, rather
than the side-to-side strokes of the hindflippers typical of most phocids. Leopard seals mostly sleep or are
otherwise inactive when out of the water, but will move in a serpentine slithering manner across ice, and will
toboggan like penguins.
Leopard seals are probably best known for their habits of preying upon penguins. The diet is actually quite
varied and changes with seasonal and local abundance of prey. Leopard seals will consume krill, fish, squid,
penguins, and young seals, and will occasionally scavenge from carcasses of whales. Most prey is caught
in the water.
Exploitation: Leopard seals are only taken in small numbers for scientific research and have never been
the target of more than minor commercial activities.
IUCN Status: Insufficiently known.
294 Marine Mammals of the World

Leptonychotes weddellii (Lesson, 1826) PHOC Lept 1 SLW

FAO Names: En - Weddell seal; Fr - Phoque de Weddell; Sp - Foca de Weddell.

Fig. 574 Leptonychotes weddellii

Distinctive Characteristics: Female Weddell

seals tend to be slightly larger and heavier than
males, but not enough to distinguish the sexes.
Much of the year the body is sufficiently plump that
the head appears disproportionately small. How-
ever, extensive weight loss during the spring
breeding season makes the size of the head less
useful. There is no discernable demarcation of the
forehead. Several features contribute to a cat-like
appearance: the very short and blunt muzzle,
large and fairly close-set eyes, a sparse number
of inconspicuous short vibrissae, and a mouthline DORSAL VIEW WITH MANDIBLE
that is turned up at the corners. The foreflippers
are more pointed and angular than those of north-
ern phocids, and are proportionately the shortest
of any antarctic phocid.
Adults are generally dark silver-grey above and
off-white below, with variable spotting, streaking,
and blotching. These markings are lighter on the
back, heavier on the sides, and sometimes con-
tinuous on the undersides. Dorsal colour pro-
gresses from bluish black just after moulting to
brownish grey just prior. The muzzle, from the
nostrils to the mouth and mystacial area, is usually
pale, as are crescent-shaped markings over the VENTRAL VIEW WIHT MANDIBLE
eyes. Pups are born in a woolly silver-grey coat,
with a darker swath along the midline of the back.
They shed the lanugo for the adult pelage in 1 to
4 weeks.
The dental formula is I 2/2, C1/1, PC 5/5.

LATERAL VIEW WITH MANDIBLE

Fig. 575 Skull

Carnivora - Pinnipedia Phocidae 295

Can be confused with: Of the 4 phocids that share the Weddell seal’s range, Ross (p. 290) and crabeater
(p. 288) seals are the most similar (leopard and southern elephant seals are easy to distinguish). Note the
proportionately larger and wider neck and head, and stripes of the Ross seal; and for the other species,
characteristics of the muzzle, head, neck, colour pattern, flippers, and vibrissae.
Size: Adult males reach 2.9 m in length, females 3.3 m. Adults in their prime weigh 400 to 450 kg, with a
wide seasonal fluctuation. Newborns are 1.5 m long and average 29 kg.
Geographical Distribution: Circumpolar and widespread in the Southern Hemisphere, Weddell seals occur
in large numbers on fast ice, right up to the Antarctic continent, and offshore through the pack ice to the
seasonally shifting limits of the Antarctic Convergence, including many seasonally ice-free islands along the
Antarctic Peninsula.

Areas of possible extralimital records

Fig. 576
Biology and Behaviour: Weddell seals breed from September through November, depending on the
locality; those in lower latitudes pup earlier. Males set up territories in the water around access holes in the
ice used by females.
Weddell seals are not very social when out of the water, avoiding physical contact most of the time. The
only copulation that has been observed occurred underwater. They may congregate in groups on fast ice
near access holes to the water.If disturbed when out of the water Weddell seals often roll onto a side and
arch their neck and chest, raising the head to look around. There is some debate over whether or not this
species is migratory. Some individuals remain in residence year round in the fast ice. Others, particularly
newly weaned and subadult animals, move north from the continent into the winter pack ice.
Weddell seals can dive very deeply (to 700 m), and to hold their breath for up to 82 minutes. The deep diving
abilities are helpful in finding breathing holes and obtaining important prey such as the huge Antarctic cod.
The diet of Weddell seals consists mostly of fish, with smaller amounts of squid and other invertebrates
rounding out their fare.
Exploitation: Weddell seals have never been exploited by full-scale commercial sealing. Throughout the
Antarctic they have been relied upon by early explorers and scientific programmes as a food source for
people, and more recently for sled dogs. Small numbers are regularly taken for research purposes. These
and all other Antarctic seals are protected by the Convention on Conservation of Antarctic Seals.
IUCN Status: Insufficiently known.

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