Botanists on a field trip, collecting plant specimens in a herbarium press.
A herbarium is a building that contains a collection of dried plant samples commonly referred to as plant specimens. Herbaria are responsible for maintaining the extensive collection of pressed, dried plant voucher specimens mounted on boards and labelled for scientific studies.
Thousands of herbarium plant specimens have been collected all around the world. These specimens are dried and carefully mounted on cardboard sheets along with the information relating to who collected them and where and when they were collected. The specimens are filed in shelves in large cupboards according to which plant family they belong to.
Herbarium plant specimens are used to describe species. Each specimen represents how a specific plant species looks like in the different areas where it has been collected.
They also inform us about the distribution of individual species over time. The species distribution is plotted on a map. Each specimen of a specific plant species is represented by a dot on a map.
Great White Shark (Carcharodon carcharias)
The Great white sharks are the largest known predatory fish and are probably South Africa's most famous shark family, playing a significant role at the top of the marine food chain. The Great white sharks are found worldwide in temperate and subtropical waters. In South Africa, Great whites are most frequent in False Bay, Gansbaai, Mossel Bay and Bird Island in Algoa Bay. They have a large torpedo-shaped, streamlined body and for steering and balancing they use their caudal and pectoral fins. They cruise seamlessly through water for long periods of time but can swim very fast in order to catch prey. The back of their bodies have a grey colour and the front of their body is white. The mix of these two colours acts a protective camouflage when they hunt for prey, they are able to blend in with their surrounding environment and remain unnoticeable.
The great white shark has no parental care. At birth the pups (baby sharks) are as long as an adult male (1.5m) are able to look after themselves and hunt for their own food. Pups feed on fish, cephalopods like squid and octopus. Many pups do not survive the first twelve months as they get preyed upon by bigger predators including other great white sharks. Adult great white sharks feed on bony fish and sea mammals (mainly sea lions, seals and dolphins).
They have no movable eyelids but protect their eyes by rolling them backwards when feeding. The teeth of the Great White are large, with a jagged edge like a saw or similar to the blades of a saw or sharp bread knife edges. Despite having 300 teeth, they do not chew their food but rip their prey into small-sized pieces that are swallowed whole. The hunting of Great white sharks for their fins, teeth and as trophies in South African waters is prohibited as they are listed as Vulnerable species on the International Union for Conservation of Nature (IUCN) Red List of threatened species.
The South African Institute for Aquatic Biodiversity (SAIAB) supports research on white Great white sharks. The Great white is among the 22 species of sharks tagged through SAIAB’s Acoustic Tracking Array Platform (ATAP) to gather more information on shark movements and population size. Information gathered by ATAP researchers is also used to facilitate the most effective protection of this species as well as the fragile marine ecosystems in which they live in by informing the government on critical areas they use as their habitat – government is then able to develop what is known as Marine Protected Areas (MPAs). MPAs are areas of the coastline or ocean that are specially protected for the benefit of people and the marine animals living there by not allowing certain activities such as fishing in those areas.
The SAIAB’s National Fish Collection has 5 catalogued specimens, 5 jaws of the Great White shark including the only record of the albino great white shark. The SAIAB’s National Aquatic Biobank has about 20 tissue samples of Great white sharks and these form part of the resource for researchers who study the naming, defining and classifying fish based on their shared characteristics.
African Penguin Spheniscus demersus
The handsome black-and-white African Penguin is endemic to mainland Africa and is the continent’s only breeding penguin species. This flightless bird feeds on pelagic fish, especially anchovies and sardines. It often hunts these fish in coordinated flocks, surrounding the shoals and forcing them into tightly packed ‘bait balls’ that the penguins can then plunder. This penguin nests only along the coasts of South Africa and Namibia, typically on offshore islands but a few mainland colonies exist, for example at Boulders and Stony Point in the Western Cape.
At the beginning of the 20th century the total population of this endearing bird was estimated at over one million individuals. Subsequent to this the species has undergone a catastrophic decrease and currently numbers less than 20 000 breeding pairs. Many threats to the species have driven this decline in fortunes. Pre-eminent amongst the current threats is over-fishing by commercial fleets of trawlers, which drastically reduce the fish stocks available to the penguins. Another major danger is pollution in the form of oil pollution from seagoing vessels. Oil clogs the plumage of the penguins eliminating the water-proofing essential to swim in these cold oceans resulting in death to oiled penguins unless they are taken into captivity, cleaned and rehabilitated for release into the wild again.
A further factor compounding the conservation dilemma faced by the penguins is that in recent years their favourite prey fish have moved away from the west coast of South Africa and more towards the southern coast of the country. This is problematic for the birds because most of their breeding islands are situated off the west coast. This shift in prey is particularly disadvantageous to juvenile penguins, which are ancestrally ‘programmed’ to move up the west coast of South Africa in search of prey that is no longer abundant in this area. This has been identified as an example of an ‘ecological trap’. The reason why fish stocks have shifted to the south is unknown but may be related to climate change or over-fishing.
Key conservation measures to protect the remaining penguins include reducing commercial fishing pressures, especially around breeding locations, attempts to establish mainland breeding colonies along the south coast, minimizing the dangers of oil pollution, and ensuring that penguins that are taken into captivity due to oiling, starvation or other causes are efficiently rehabilitated and released.