Seaweeds or marine algae are relatively simple plants. The smallest consist of only a single cell, or the plant body (thallus) may be a simple filament, a broad sheet, a frond with flat or cylindrical divisions, or a close or crumpled crust on rock, shell, or other substratum. Even the largest absorb food over the whole surface, the rootlike portion being an attaching holdfast only. Some, for instance Corallina, that are hard and brittle with limy salts extracted from the sea, are related to the nullipores of coral reefs. In others, for example Carpophyllum, hollow vesicles buoy up the thallus towards the light; in many, watery or mucilaginous contents reduce the risk of drying out at low tide. Reproduction is by single cells produced over wide areas of the surface, as in bull kelp, in restricted patches, as in Stenogramme, or on special branchlets, as in Carpophyllum. Classification is based on reproductive pattern, but three large groups are distinguished by colour. All contain chlorophyll clearly seen in the green Chlorophyta but obscured by brown pigments in the Phaeophyta and by red of different shades in the Rhodophyta. Recorded numbers of species in New Zealand are: green, 205; brown, 127; and red, 389. About 40 per cent are endemic and at least a hundred species are shared with Australia.

Microscopic seaweeds floating in the surface layers of the sea form the phytoplankton which traps the energy of the sun and is the basic food of all sea animals. In New Zealand waters 198 species have been recorded, of which 125 are Bacillariophyceae (diatoms) and 63 Dinophyceae. Phytoplankters sometimes occur in large discoloured patches and give the brown tint to blown foam on west-coast beaches. Their abundance varies greatly in different current zones.

Larger seaweeds are mostly firmly attached, each where conditions suit it best. The bladder kelp, which reaches a length of 100 ft or more, is common about Cook and Foveaux Straits and the east side of the South Island, but is not known to grow on the west coast of the South Island or north of Castlepoint. It has a south circumpolar distribution, but extends up the west coast of America and as far north as California, and a closely related species grows on the west coast of South Africa. Marginariella, an endemic genus of two species, and the strongly acid Desmarestia, whose relatives are widespread in temperate regions of both hemispheres, and a number of red seaweeds are likewise restricted to southern New Zealand. Carpophyllum plumosum, a very common large brown weed of the North Island east coast, is unknown in the South Island, though it grows at Chatham Islands.

Durvillea antarctica, the bull kelp, is a species on rough coasts, and Hormosira banksii, the necklace seaweed, grows only where it is sheltered from heavy seas. Upper intertidal levels are occupied by species such as Porphyra columbina, the karengo, that tolerate long exposure to air, light, and rain. The falling tide uncovers plants that are successively less tolerant, for example, Hormosira and the green velvety Codiums. The green grape seaweed, Caulerpa sedoides, is left dry only at very low tides. Many weeds, both tough, like Zonaria, or delicate in texture, like Laingia, are sublittoral, growing below the level of low spring tides. Karengo is seasonal, appearing in winter as narrow silky ribbons which, by early spring, have grown into broad blackish-purple sheets a foot or so long; by summer all has worn off except the holdfast with a ragged yellowish green frill. Desmarestia appears on low-tide rocks in early winter as a delicate branching frond fringed with soft hairs; by summer it is 6 ft long, dark brown, hairless, and with a stout midrib in each segment. Scytosiphon, like a string of miniature brown sausages, and Adenocystis, the sea bomb, are also annual seaweeds.

The slope and particle size of soft beaches and flats depend both on the power of the wave attack and on the ability of rivers and coastal currents to supply new materials. Beaches can best be classified according to their topography and degree of shelter, and the burrowing animals that distinguish them accord pretty well with such a division. The above map shows an example of the occurrence of open, protected, and enclosed soft shores. Open beaches are those of medium to coarse sand, mobile, and exposed to wave attack. Protected beaches are wider flats sheltered under the lee of promontories and islands. Their sand is finer grained, less wave shifted, and often stable enough to carry seagrass or Zostera at the lower edge. Under the full protection of the land mass are the sheltered shores of harbours, generally estuaries of lagoons, having a high proportion of silt and mud and, towards low water, becoming very soft. In the furthest backwaters, built by river deposition under little wave attack, are the tidal flats fringed with mangrove in the north and Salicornia in the south, succeeded by beds of sedge and rush and ultimately salt meadow.

Open Beaches

The great majority of burrowing animals belong to the bivalve and gastropod Mollusca, and to the Crustacea, Echinodermata, and the worms. Open beaches right through New Zealand are characterised by the fast-burrowing streamlined bivalve, Amphidesma subtriangulata, the tuatua. This may be replaced on the North Island west coast and in part of the South by the larger and faster toheroa, Amphidesma ventricosa.

At low tide is found the zigzag cockle, Tawera spissa, and just beyond it the trough shells (Mactridae) and several Tellinidae. Burrowing gastropods include the carnivorous Tonna haurakiensis and the helmet shells (Xenophalium), the deposit-feeding Zethalia, and the ciliary feeding Struthiolaria. The Crustacea of open beaches are typically the amphipodan sandhopper, Talorchestia quoyana, and the beach lice, Scyphax and Actaecia, near high tide. Active carnivorous Sphaeromidae and Cirolanidae occur at mid-level with the sandlicking or fine-deposit-feeding amphipods of the Haustoriidae and Phoxocephalidae further down. Larger burrowing crustaceans are the carnivores, the mantis shrimp, Lysiosquilla, and the swimming crab, Ovalipes, together with the frail, filter-feeding ghost shrimp, Callianassa. The chief echinoderms are the cake urchin, Arachnoides zelandicus. Worms include fast-burrowing carnivorous Nephtyidae and Glyceridae, and sand swallowers, such as Armandia.

Protected Beaches

Protected beaches carry by far the richest burrowing fauna. On the middle slope is found characteristically the third species of Amphidesma, the pipi, A. australe. Below it and freely distributed over the wide middle beach is the plump, shallow-burrowing cockle, Chione stutchburyi, and with it the long-siphoned deep-burrowing tellinid, Macomona liliana. Low tidal bivalves include Dosinia subrosea, Myadora striata, and Angulus gaimardi. The gastropods include not only Struthiolaria but also the carnivores Baryspira, Pervicacia, and Alcithoe. There are many polychaete worms, most characteristically the deposit feeders of the Ariciidae, and the makers of permanent tubes, such as Eunicidae (Onuphis and Diopatra), the long-tentacled Terebellidae, and the sand-tubed Maldanidae, Owenia fusiformis and Pectinaria australis. Scale worms include Sigalion and Lepidaesthenia, while the most active worms of all are the proboscis-shooting Glycera and Aglaophamus. Feeding by waving slender palps above the sand level are the Spionidae, and in coarser sand higher on the beach lives Platynereis australis.

Echinoderms feeding on the organic surface deposits are the brittle star, Amphiura aster, the heart urchin, Echinocardium australe, and the wormlike burrowing sea cucumber, Trochodota. On northern beaches live the spiny-armed sand star, Astropecten polyacanthus, and the large yellow hemichordate, Balanoglossuss australiensis, making continuous castings of defaecated mud. A similar diet is taken by the unsegmented worms, Urechis and Sipunculus.

Enclosed Shores

The muddy sand flats of harbours are typified by the bivalves, Chione and Macomona, and by the oval trough shell, Mactra ovata, where there is more clay. In the sand the fan mussel, Atrina zelandica, lies vertically buried, attached to sand grains with its dense byssus. In countless numbers is the small bivalve, Nucula, and deep in softer muds is the thin-shelled Solenomya parkinsoni.

The Gastropoda include as roving carnivores the Cominella species, glandiformis and adspersa, and the surface-trailing deposit feeders, Zeacumantus lutolentus, and the topshell, Zediloma subrostrata. Among the sticky muds of mangroves and salt swamp is the pulmonate mudsnail, Amphibola crenata, and in salt-rush beds a second primitive pulmonate, Ophicardelus.

Low tidal Zostera flats have a rich gastropod fauna, with the bubble shells, Haminoea and Quibulla, deposit feeders casting jellylike spawn, and sluglike Philine with internal shell, a carnivore on bivalves. Cropping sea grass at the surface is sea hare, Bursatella glauca, the small comical Micrzlenchus huttoni, and tiny rissoids. At low water is often found the mobile swimming scallop, Pecten novaezelandiae.

The crabs of Zostera flat are very abundant, particularly the stalk-eyed Hemiplax hirtipes, the pillbox crab, Halicarcinus cooki, and the small Hemigrapsus cranulatus. Higher up, in salt swamps and mid-tidal flats, is the burrowing crab, Helice crassa. Abundant at low water in soft mud are not only Lysiosquilla but also the familiar snapping shrimp, Alpheus.

Typical burrowing worms found on harbour shores are the Spionidae Nereidae with several species, Cirratulidae, Glyceridae and Notomastidae. On southern flats occurs the lugworm, Arenicola affinis.

by John Edward Morton, M.SC.(N.Z.), PH.D., D.SC. (LOND.), Professor and Head of Department of Zoology, University of Auckland.

SEATO, see INTERNATIONAL RELATIONS .

On hard shores a combination of the tides and other factors produces a clearcut zonation. The living girdle is a many-stranded one, horizontally divided into separate zones or belts, characterised by quite distinctive animals and plants. Consideration of the animals must always involve the background of the plants and, for the marine ecologist, the flora and fauna are inseparably intermingled. The composition and order of the zones is under the fundamental control of the tides. But there are many other factors as well that influence the ecology of the shore. Zones are modified by the steepness and aspect of the rocks, by sun exposure or shade, by the geological character, by the sweeping of currents, the scouring of sand, and the variations in turbidity and salinity. The chief contrast we must draw is between “exposed” and “sheltered” coasts. The effects of surf pounding, splash, and spray bring about great changes in hard-shore populations. New Zealand runs through 12 degrees of latitude, so that another important variable is that of sea temperature and hydrography, responsible for large changes in shore patterns from north to south.

Ecologists recognise three major zones on hard shores, which, broadly speaking, are under tidal control. The uppermost zone or littoral fringe is that part of the shore above average high-water level. The lowermost zone or sub-littoral fringe lies between average low water and extreme low water of spring tides. The mid-littoral zone is that large part of the shore between average high and average low water. On exposed shores, however, these zones have no strict correspondence with tidal level, for under the influence of splash and spray their upper limits may be raised many feet higher. Indeed, the zones may be defined on a biological basis only by the local limits that the plants and animals, under a complex combination of environmental factors, happen to reach.

We may select an exposed shore and a sheltered shore, both from the North and from the South Island, illustrating on these the typical animals, whether fixed and zone-forming, or mobile and freely wandering. A northern shore line of moderate shelter (Diag. 1) shows the herbivorous gastropods, Melaraphe oliveri and Nerita melanotragus, scraping the rock face for lichens and algae in the littoral fringe. The upper part of the mid-littoral zone is clad with acorn barnacles, sessile Crustacea surrounded by a hard shell, and filtering off plankton with the casting nets of their feathery limbs. The highest species, much better developed under surf, is Chamaesipho brunnea. Next comes the smaller C. columna and, lowest of the three, Elminius plicatus. The barnacle zone may be cut through by a thick belt of that sessile filter-feeding bivalve, the rock oyster, Crassostrea glomerata. From the lower middle shore and downwards grow successive belts of algae.

In the barnacle zone and upon the algae, graze many species of herbivorous gastropods. Mingling high up with Nerita is the limpet, Cellana ornata. Through the oyster zone downwards will always be found the snake's skin chiton, Sypharochiton pellis-serpentis, and the topshells, Melagraphia aethiops. Further down appears a second limpet, Cellana radians, while grazing on the algae, Hormosira and Corallina, are the cat's eye, Lunella smaragda, and the long-spired cerithiid snail, Zeacumantus subcarinatus. On the paintlike coralline algae at low water graze the pauas, Haliotis, the topshell, Trochus viridis, and the large cousin of the cat's eye, Cookia sulcata. Carnivorous snails include the thaids, Lepsiella scobina, boring the shells of barnacles and oysters, and Lepsia haustrum, feeding on herbivorous gastropods as well. Several species of Cominella act as scavengers, as do the hermit crabs in pools. Echinoderms include the familiar cushion star, Patiriella regularis, and at low water the coralline grazing sea urchin, Evechinus chloroticus.

Our more exposed Auckland shore (Diag. 2) is typified by the Auckland west coast, the rocks being shown covered with sand up to the mid-littoral and cutting out the bull kelp, Durvillea, and the profusion of algae found growing under full wave exposure. In the littoral fringe are fast-running purple crabs, Leptograpsus variegatus, while the barnacle zone has the same three species as on sheltered shores, with Chamaesipho brunnea especially well developed. The little mussel, Modiolus neozelandicus, forms a jet-black band higher up, and towards low water appears the large green mussel, Mytilus (Perna) canaliculus. Just above the sand level may be found two belts of filter-feeding tubeworms, Pomatoceros cariniferus, with hard shelly tubes, and the massive sandy tubes of Sabellaria kaiparaensis. Roving animals include several limpets, Notoacmea pileopsis in the littoral fringe, then Cellana ornata, Notoacmea parviconoidea, Siphonaria zelandica, Patelloida corticata, and Radiacmea inconspicua. The large thaid gastropod, Neothais scalaris, feeds on the mussels, as does the buff or mauve starfish, Stichaster australis.

A sheltered shore in the South Island will show many of the same organisms as in the north, but with many variations and additions, as shown by the example from Otago Harbour (Diag. 3). The barnacle zone is thin, with Chamaesipho brunnea absent south of Kaikoura. In mats of Bostrychia above C. columna are the leathery slug, Onchidella nigricans, the snail, Rissellopsis varia, the minute bivalve, Lasaea, and the black-spired snail, Zeacumantus subcarinatus. The large pulmonate limpet, Benhamina obliquata, is in the south a familiar occupant of shady crevices in the barnacle zone. Where the shore is current-swept appears the barnacle, Elminius plicatus (common also in the north), with below it the encrusting bivalvess the navy mussel, Mytilus edulis aoteanus, the ribbed mussel, Aulacomya maoriana, and the Dunedin rock oyster Ostrea hefferdi.

In the sub-littoral fringe the encrusting life is vastly rich, with sponges, polyzoans, and ascidians as filter feeders and numerous anemones and hydroids as sedentary carnivores. Conspicuous along with the huge thalli of the bladder kelp, Macrocystis, are the yard-long stalks of the sea tulip, the ascidian, Pyura pachydermatina. This species and Ostrea hefferdi are chiefly denizens of the Otago coast. Otherwise the same pattern serves well for sheltered coasts from Cook Strait southwards.

Exposed shores have a general similarity through much of the New Zealand coast. Diag. 4 shows such a pattern from Banks Peninsula. It is dominated in the sub-littoral fringe by the two species of bull kelp, Durvillea antarctica and D. willana, the latter confined to the south. The chief zoning animals are the barnacles and mussels. Modiolus, Mytilus edulis, and Aulacomya often interrupt the wide extent of barnacles, but the chief zoning mussel at low water Mytilus (Perna) canaliculus, forming large byssus-attached sheets. Around it are not only Neothais and starfish, but the fast red crab, Plagusia capensis, and large colourful anemones, such as Cradactis magna. The bull kelp holdfasts have a rich eroding fauna of worms, isopods, siphonariid limpets, and chitons.

The encrusting and roving animals under movable stones (Diag. 5) represent another realm that we must briefly consider. In smooth boulder beaches at mid-tide, grapsid and other crabs are abundant, with a wide range of topshells, such as Zediloma atrovirens, Z. digna, Z. arida, and Anisodiloma lugubris. The fragile limpets, Notoacmea daedala and Atalacmea fragilis, are common. In the sub-littoral fringe the lower surface of boulders is richly encrusted with ciliary feeding invertebrates. Such are the sponges in vivid scarlets, yellows, and browns, the lacelike crusts or bushy tufts of polyzoans, the pink brachiopods (Terebratella), byssus-attached bivalves (ark shells, saddle oysters, and fan scallops), ciliary feeding gastropods, such as slipper and saucer limpets and vermetids, and the wealth of brightly coloured ascidians, both simple and compound. Roving animals sheltering under rocks include the rockfish, Acanthoclinus, blennies, and sucker fish, and a great wealth of crabs of the Cancridae, Grapsidae and Xanthidae, as well as the familiar green “half-crab” Petrolisthes. Starfish, such as Coscinasterias and Allostichaster, and brittle stars (Ophionereis and Pectinura) and the sea cucumber, Stichopus, are common. Encrusting animals include carnivores, as well as ciliary feeders: anemones, hydroids, and even cup corals, Culicia and Flabellum. Molluscan predators, such as carnivorous snails and colourful nudibranchs, are adapted for specific diets upon almost every kind of sponge, coelenterate, ascidian, and polyzoan.

Softer rocks, such as mudstones, are pitted and bored by bivalve molluscs, such as the low tidal piddocks, Pholadidea spathulata, P. tridens, and Anchomasa similis, and the date mussel, Zelithophaga truncata. At mid-tide level, the amphipod crustacean, Sphaeroma quoyanum, makes smaller pits. The disused burrows of piddocks are occupied by other species of nestling bivalves (Notirus, Notopaphia) that do not actively bore, and by terebellid and cirratulid worms.

The animals of the seashore include those species confined to or spreading into the intertidal zone, that narrow fringe of the coastline over which the tide rises and falls twice daily. The tides give a unique character to the ecology of the shore. A sequence of highly adapted animals and plants, of many different classes and life forms, girdles the whole land mass. Shores are divided first and most fundamentally into the two categories, hard and soft. Few species overlap between the two and the conditions of life in the two habitats are utterly different.

Seals were first reported in New Zealand by Captain Cook who found in Dusky Sound “great numbers, about the bay, on the small rocks and isles near the sea coast”. In 1792–93, 19 years after Cook's discovery, a party of sealers spent 10 months in the Sound, securing 4,500 seals which they skinned for the China market. Sealing later spread to islands in Foveaux Strait, to Stewart Island, and to the deep harbours of the west coast. During the early period, when southern New Zealand was the centre of interest, most of the sealers came from Australian ports; in 1804 American vessels were first reported in the trade, with the sub-Antarctic islands as their goal. About that year some 60,000 skins were taken from Antipodes Island, and, during the following decade, the Bounty, Auckland, Chatham, Macquarie, and Campbell Islands were in turn visited and divested of their seals. Fur seals were usually the first to be taken, but oiling parties with their trypots and barrels followed closely to make use of the elephant seals and sea lions. After 1813 most of the trade was centred on Macquarie Island, where oiling alone remained profitable; on the South Island and elsewhere in the sub-Antarctic islands only sporadic visits were made to clear up remnants of the stock as a source of profit incidental to other forms of trading.

The hardships of the sealers have been recounted in many authentic records; the occupation was undoubtedly hazardous, and probably with little reward to those who saw it at first hand. Parties left for a season or a year on remote islands were often forgotten or abandoned by accident; one group was left on the bare and waterless Bounty Islands for a year, and parties survived on the Solanders for five years, and on the Snares for seven years, according to contemporary accounts. Sealing ventures continued throughout the nineteenth century, realising only very small quantities of skins and oil, and ceased with the protection of all species early in the present century. Although protection has from time to time been withdrawn from fur seals, to prevent an increase in their numbers, there is little chance of the species becoming economically important in the near future.

by Bernard Stonehouse, B.SC.(LOND.), M.A., D.PHIL.(OXON.), Reader in Zoology, University of Canterbury.

• History of Otago, McLintock, A. H. (1949)
• Murihiku, McNab, R. (1909)
• Old Whaling Days, McNab, R. (1913)
• Rakiura, Howard, B. (1940).

The breeding habits of the three New Zealand species of seals are very similar. Early in the breeding season, about October or November, the large bulls haul out of the water and take up territories along beaches and rocky shores. Each defends its area against incursion by neighbours and fights off younger bulls which attempt to carve out territories of their own. Three to five weeks later the cows begin to arrive, forming groups or harems of 10 to 15 within the territories. The old bulls defend their harems against the attentions of the younger bulls, rounding up the straying cows and fighting intruders almost continuously throughout the summer, with considerable expenditure of energy. They live only on their reserves of fat during the breeding season which may extend over three months or more.

The cows give birth to their pups shortly after leaving the water, and usually mate within a few days or weeks of parturition. The fertilised egg of the elephant seal (probably also of the other species) remains unattached in the uterus for several weeks before implanting, so that development begins late in summer, and the foetus, with a true gestation period of nine to 10 months, is ready for birth 11 to 12 months after fertilisation. The pup of the elephant seal weighs about 100 lb at birth and measures slightly over 4 ft from nose to tail. Its birth weight doubles in 11 days (the human infant doubles its birth weight in six months), and the mother ceases to feed the pup after three to four weeks. Its downy birth coat is shed rapidly during the first week of life (or may even be lost before it is born), and the pup is ready for the sea at an age of six to eight weeks. Fur seals and sea lions keep their young by them for several months; the pups apparently grow more slowly and take longer to reach independence.

Other species of seals visit New Zealand from time to time; most frequently reported are young sea leopards (Hydrurga leptonyx) and Weddell seals (Leptonychotes weddelli) from the Antarctic. Sea leopards are also seen often about the sub-Antarctic islands.

The sea lion of New Zealand's sub-Antarctic, Hooker's sea lion Phocarctos hookeri, was named after the botanist of Ross's naval survey expedition which first brought specimens back for scientific study. This animal breeds in large colonies at Carnley Harbour and Enderby Island, in the Auckland Islands group. A few breed on Campbell Island, and larger groups of non-breeding adults are reported from the Snares and other sub-Antarctic islands. Sea lions are generally larger and heavier than fur seals; large males measure up to 10 ft and have a characteristic “mane”; mature females range from 5 to 7 ft in length. They lack the dense underpelt which fur seals have; their hide was, however, tanned and used as a strong, supple leather for clothing. Hooker's sea lion is grey or fawn, fading to white; the species is peculiar to the New Zealand area, although closely related to similar animals on other islands in the southern oceans. Little is known of its habits or numbers.

Elephant seals or sea elephants (so called from the large, inflatable proboscis of the males during the breeding season) are found throughout the sub-Antarctic islands of the Atlantic, Indian, and Pacific Oceans. In the New Zealand region they breed in large concentrations on Campbell and Macquarie Islands, and in 1949 a small breeding colony was reported to have formed on the Antipodes Islands. The largest bulls of this species reach lengths of 20 ft or more; cows are seldom longer than 10 ft. The hair is coarse and short. Old bulls are often heavily scarred from fighting and lose much of the hair from their neck and face. Their colour is buff or brown, but may vary from silver grey to fawn in younger animals; cows and young bulls are similar in shape and colour, and the distinctive inflatable proboscis of the mature bull appears only in the sixth or seventh year. Like all other Phocids, elephant seals lack external ears. Their hind limbs trail backward both in walking and in swimming; the forelimbs are reduced in comparison with those of the Otariidae, and the animals move by undulating the muscles of the trunk. The species has recently been made the subject of an intensive study by Australian biologists on Macquarie Island (see papers by Carrick and others in CSIRO Wildlife Research 7 (2), 1962).

The New Zealand fur seal is peculiar to this country, although very similar to a closely related form inhabiting southern Australia and Tasmania. Little research has been done and the true status, habits, food, and numbers of the New Zealand fur seal are almost unknown. It appears at present to be thriving and increasing. Two small breeding colonies are known in the South Island, and several non-breeding accumulations of animals are reported; larger breeding colonies are known on the Chatham, Snares, and Auckland Islands, and breeding may also occur on Campbell and Macquarie Islands. Population may number from 40,000 to 50,000. Mature bulls are between 6 and 7 ft long. Cows and young bulls seldom exceed 5ft. The fur is grey-brown, with a dense buff, stone-coloured, or reddish under-pelt; nose and flippers are dark brown shading to black. The tiny pointed ears, almost hidden among the head fur, and the forward-pointing hind flippers are diagnostic of the family Otariidae to which this species belongs. The rich fur, sharply pointed muzzle, and swept-back whiskers distinguish it from the sea lion, which it otherwise resembles in shape and character. Fur seals are most characteristically seen on rocky headlands and reefs, where they drape themselves in seemingly comfortless positions for sleep. Quarrelsome and aggressive amongst themselves, they are uneasy in the presence of man and usually move back into the sea when he approaches. In the water their powerful shoulders and foreflippers propel them with speed and great manoeuvrability; the hind feet, which are used much in walking over the rocks, play a lesser role when the animals are swimming.

Seal skins and oil were among the first of New Zealand's natural resources to appear in world markets. The early enterprises of sealers, here as elsewhere, were conducted in secrecy; consequently the records are few. But it seems probable that commercial sealers first hunted in New Zealand waters about 1792. The industry flourished briefly; in less than 30 years the seals were hunted almost to extinction both in New Zealand and in the sub-Antarctic islands. Only in recent years have they been allowed, under legal protection, to increase in numbers and approach their former population strength.

By modern systematists, seals are grouped in the order Pinnipedia, although some biologists would still prefer to regard them as aquatic members of the order Carnivora. Superficially, they are remarkably doglike, and the pups of many species bark as though to claim affinities with the dogs. Seals are, however, considerably modified both internally and externally for life in the sea. Their limbs are paddles, their shape is streamlined, and their blood system, muscles, and skin show many adaptations which help them to dive and swim efficiently. Under water the heart slows to a rate of three to six beats per minute. Some seals, possibly all, have a muscular collar on the diaphragm which constricts their blood system, so that circulation is maintained only in the vessels of the head during a dive; the muscles of viscera and limbs work under anaerobic conditions, and thus all available oxygen is reserved for the brain. Seals have more blood than do land animals of similar size, and so take down considerable stores of oxygen when they dive.

Most seals live in cold water, where food is plentiful; New Zealand is toward the northern edge of the range where seals would be expected, although tropical and subtropical species are known. Living in waters colder than their own bodies, they require insulation to prevent excessive heat loss; hence the thick blubber, hide, and fur which attracted the sealing gangs of the eighteenth and nineteenth centuries. Fur is found only on sub-Antarctic animals, together with comparatively thin blubber; in climates where icing might become a problem seals have a much thinner covering of hair, without the dense under-pelt which furriers value, and insulation is maintained by a much thicker layer of blubber. On the sub-Antarctic islands of New Zealand both fur-yielding and oil-yielding species were found; in New Zealand itself only fur seals were of any commercial importance, although it is possible that sea lions (which yield oil and hides) may also have been taken at one time from the west coast of the South Island.

Biologically, seals are divided into three families of which one (Odobenidae, the walruses) is found only in the Northern Hemisphere. The remaining families, Otariidae, the eared seals (including fur seals and sea lions), and Phocidae, the so-called “true seals”, have a world-wide distribution, with a tendency to congregate in the colder waters of high-latitude seas and polar currents. Three species of seals breed at present in the New Zealand region (including the sub-Antarctic islands): two are eared seals, and the third is the largest of the true or Phocid seals, the sea elephant. Only one species, the New Zealand fur seal Arctocephalus forsteri, breeds north of the forty-eighth parallel in the South Island; the other two are entirely sub-Antarctic in range and are seldom seen even as stragglers on the main islands of New Zealand.

The seals of the Provinces of New Ulster and New Munster were engraved by Benjamin Wyon and sent out with the second Public Seal in 1848. They were used until the creation of six new provinces under the 1852 Constitution Act. Each province had its own seal and these remained in use until the provinces were abolished. After the abolition in 1876 the seals were lost sight of for many years until C. E. Mackay, of Wanganui, made inquiries in 1904 which resulted in all of the seals, except those of Westland and Southland, being located. Later, an impression of the West-land seal was found and in 1940 the Southland provincial seal was located.

Seals are used by some local, ecclesiastical, educational bodies, societies, and associations.

by John Sidney Gully, M.A., DIP.N.Z.L.S., Assistant Chief Librarian, General Assembly Library, Wellington.

• New Zealand Centennial News, Nos. 8, 9, and 12.