Supplementary information
Southern Ocean and Macquarie Island
The lower latitudes of the Southern Ocean are cold, wet and windy most of the time but have a brief warmer summer.
On land during spring and summer there is frantic activity from all animals as they eat, mate and prepare for the winter.
Animals living in the sea have an environment of constant temperature and salinity but in the vast ocean their main challenge is finding each other, finding food and finding their way.
| Vegetation
Tussock grasses, dwarf plants and mosses are common on the islands. Constant wind and low temperatures prevents the growth of taller trees. Beds of kelp grow in the shallow waters surrounding the islands. The ocean waters can only sustain microscopic, floating single-cell plants called phytoplankton. |
Midget spider
Parafroneta marrineri
The midget spider is 3–4 mm long and captures minute insects in small sheet webs. The webs are up to 40 mm across, close to the ground and near rocks or grass tussocks, to shelter them from the elements. Most of the spider’s water needs come from dew or rain collected on the web. The remainder comes from its prey. Long inactive periods in its shelter conserve energy and water.
In summer the male spider wanders in search of a mate during periods of higher humidity or after rain. This protects it from dehydration.
Small spiders lose water at a faster rate than large spiders due to their body surface area compared to their weight. Some small spiders have developed hard plates on the abdomen to reduce the water loss.
In winter the adults die and the spiderlings remain dormant until spring when they grow, mature, mate and lay eggs before the next winter.
Some species of midget spiders are becoming common in cities. A few live in forests or in arid areas. Cleared grazing land provides a more suitable habitat.
Reference
Blest, A D. 1979. Linyphiidae—Mynogleninae. In The spiders of New Zealand, Part V. Otago Museum Bulletin, No. 5, Dunedin.
| Vegetation
Tussock grass Poa =grass foliosus = covered with foliage Tussock grass stems form high pedestals which are covered by narrow leaves up to a metre in length. The leaves form a dense canopy shelter and web anchors for the midget spider. |
Slender-billed prion
Pachyptila belcheri
The slender-billed prion feeds at sea during the night eating mostly crustaceans (particularly amphipods), some fish and squid. No fresh water is available and the birds drink seawater.
These birds can drink seawater because they have large, highly efficient salt glands located against the skull above the eyes. These glands desalinate the blood and secrete highly saline water into the nasal cavities and down to the bill tip. All birds possess these paired nasal glands in the orbit of the eye but in terrestrial and freshwater species these may be small and non-functional.
The birds spend most of their time at sea in Antarctic and subantarctic waters and rest on the surface of the sea. Only when they are breeding do they come to land.
The prion breeds in late spring to early autumn on islands between subantarctic and subtropical convergences in the South Indian, Atlantic and Pacific oceans. It nests in burrows in soil or under rocks or low vegetation, lining the nest with a little dry grass, feathers, leaves or twigs. Both parents incubate the only egg and attend to the young.
The main human contact is on nesting islands where they may be threatened by introduced predators, trampling by humans and grazing stock. The depleted Falkland Island prion population is now recovering after revegetation and the eradication of introduced predators.
References
Reader’s Digest complete book of Australian birds. 1990. Reader’s Digest, Sydney.
Cox, J B. 1980. Some remarks on the breeding distribution and taxonomy of the Prions (Procellariidae : Pachyphila). Records of the South Australian Museum, 18(4), 91–121.
| Vegetation
Cushion plant Azorella macquariensis azo = to dry, azorella = diminutive of Azores, macquariensis = Macquarie Island "Cushion" because it looks like a cushion! The cushion plant is made up of densely packed stiff leaflets and branchlets of equal size which grow to only 30 to 40 cm high. The very compact growth deflects the wind and helps insulate the plant just as densely packed feathers insulate the prion and help create a smooth air flow over its wings when in flight. When the prion digs burrows for breeding and protection this helps nearby plants with drainage and nutrients from bird’s droppings. |
Southern sea-devil
Ceratias tentaculatus
Ceratias = a kind of comet resembling a horn, tentaculatus = with tentacles
The female southern sea-devil can grow up to 90 cm long. It has black skin to camouflage itself and a rod with an illuminated lure resembling an invertebrate to attract other fish, crustaceans and squid. Prey is secured in its large mouth with very sharp teeth.
The sea-devil lives near the sea bed down to 2900 m. Here there is no light, and conditions—temperature, salinity, water movement—are constant.
The male grows to only 1.6 cm long. Early in its life it somehow finds a female and attaches on to the female’s body and lives by absorbing food and nutrients from the female. This procedure avoids the problem of having to keep finding each other in the vast dark sea.
The Southern sea-devil has spines growing on its skin to discourage other fish and squid from eating it.
References
Bowen, B K. 1963. The angler-fish Ceratias
holboelli from Western Australia. Journal of the Royal Society
of Western Australia, 46(3): 91–92.
Clark, M A. 1950. The bathypelagic angler fish Ceratias holboelli Kršyer.
Discovery Report, 26:1-32.
Kršyer, H. 1845. Ichthyologiske bidrag 10. Ceratias holboelli.
Naturhistorisk Tidsskrift Vol 1 part 2: 639-649.
| Vegetation
Racomitrium crispulum With no complex transport systems to move water through their bodies mosses must remain small and are often found living near water. The springtail is also small and has to live near moisture to prevent rapid dehydration. In some locations on Macquarie Island moss grows in strips at right angles to the prevailing wind direction. Fresh growth is on the protected or leeward side. Springtails shelter and live in the soil around these plants for protection. |
The giant squid is an ambush predator of fish and other squid. It has eight arms (and no tentacles) with cat-like claws to catch prey. Two arms have light organs at the tips to attract prey in the dark depths of the ocean. With its large eyes it recognises other giant squid and animals with light organs.
The squid shelters in the depths, and uses "jet-propulsion" to escape predators. Supported by the water it can grow to be 2–3 metres long as well as 3 metres across, and it is a favourite food of sperm whales.
Little is known about the habits of the giant squid but scientists suspect it mates near the sea floor and eggs are probably attached to something at the bottom near places likely to be advantageous to the hatchlings.
This world wide open-water oceanic squid prefers deep waters down to 1000 metres. It is unlikely to be affected by human activity unless over-exploitation of fish stocks reduces its food and limits its numbers.
| Vegetation
Bull kelp Durvillaea = named after a French explorer Dumont D’Erville, antarctica = grows near Antarctica "Bull" because of its large size, "kelp" is a general term for brown algae, originally "kelp" referred to ash derived from burning marine plants which are rich in soda and potash Bull kelp lives in water. It uses air spaces trapped in its long fronds to help stay afloat and near the light zone. Like the giant squid this plant is supported by water. Holdfasts or suction caps attached to rocks prevent the bull kelp from being washed away by wave and tidal action from its favourable living zone. Bull kelp is harvested in Chile and used in cooking as a sea vegetable. |
Southern right whale
Eubalaena australis
The southern right whale comes from a lineage of mammals that left the land and returned to live in the sea. It has many adaptations to enable it to live in the cold southern ocean and to survive on a very salty diet with no fresh water.
During summer the southern right whale feeds on vast amounts of small crustaceans, mainly copepods and sometimes krill, found in the nutrient-rich water near the Antarctic Convergence, about 55žS latitude. The whale skims the crustaceans from the water with its 2 m long baleen plates. It licks the baleen plates and swallows the food. The whale’s kidneys remove the large amounts of salt from the blood.
In the cold water the whale keeps warm with thick layers of blubber and reduces heat loss by slowing blood flow to its flippers, which were once arms and hands.
The only remnants of legs are small internal pelvic bones. The whale is very streamlined with almost no body hair, concealed genitals and nipples, no external ears and small eyes. Nostrils on the top of the head enables it to breathe while most of the body remains submerged.
In winter the southern right whales head to warmer water along the southern coast of Australia where they mate and where calves are born, on average every three years. Calves must swim as soon as they are born. The mother feeds them concentrated milk and they grow rapidly in preparation for their spring journey to the feeding grounds.
In the pre-European period, it was believed that particular Aboriginal people could "sing" the whales in so they could eat the highly favoured meat of the beached whale. There are whale dreaming stories in South Australia.
The southern right whale was an economically important species to the early European colonists in South Australia. Whaling stations at Encounter Bay operated for only a few decades from 1837 before it became uneconomical to hunt the greatly depleted numbers and ceased in 1871. The southern right whale has been a protected species since 1935 and numbers are increasing at about 8% each year.
| Vegetation
Phytoplankton Microscopic phytoplankton is the plant food base for all marine life and is sometimes called the "grass" of the sea. These tiny plants, with internal silicon walls, live from the surface of the ocean to a depth of about 150 m. They rely on the sun for their energy and reproduce in vast numbers when the nutrients, temperature, salinity and light reach optimum combinations. Copepods and krill rely on phytoplankton as their food source and in turn the southern right whale relies on these as its major food source. One of the largest of the worlds mammals depends almost entirely on the tiniest of plants. References: Clayton M N and King R
J (eds). 1990. Biology of marine plants, Longman
Chesire, Melbourne. |