Zooplankton are small animals which drift and move freely in the oceans, feeding on phytoplankton or other small animals. During the day they are found in deeper water, while at night they move to the surface to feed. Huge numbers of fish and crustacean eggs and larvae add to the variety of zooplankton. Most jellies feed on zooplankton and many fish, seabirds and whales must find dense patches or swarms of zooplankton in order to survive.
The juvenile Loggerhead turtle:
These turtle hatchlings are frequently thrown ashore along the Cape south coast during strong onshore South easterly Summer gales. (In the aquarium, they are 2-3 months old)
The adult Loggerhead turtle
Adults appear off Northern Kwazulu-Natal coasts from October to February. They mate at sea and females deposit their eggs in nests on the beach.
The life cycle of the Loggerhead turtle
The complete life cycle of the Loggerhead turtle is not well understood. The Agulhas current initially carries hatchlings south. Thereafter, they are widely dispersed in the South Western Indian Ocean by recirculating gyres of the Agulhas current. At approximately four years of age they return to coastal waters and change their diet from "oceanic drifters" such as jellies and "Portuguese-man-of-war" to reef organisms such as crustaceans and sponges.
Many species of fish produce floating eggs. As a result, millions of larvae and young juveniles start life as "ocean drifters". To avoid being eaten by predators, eg tuna and dolphin fish, a number of species utilise drifting flotsam for refuge. They may drift with this flotsam for many months, feeding on passing organisms and other animals which are attracted to the flotsam such as crab larvae, amphi-pods and copepods.
The Golden Kingfish
Occurs throughout the tropical Indo-Pacific south to northern KwaZulu-Natal. Juveniles frequently accompany sharks and manta rays. Grows to 110cm.
Most Jellyfish are carnivirous. They stun their prey with stinging cells on their tentacles and pass the food to their mouth which hangs from the centre of the bell. They are an important food source for turtles. Jellyfish belong to the same Phylum Cnidaria as the anenomes and blue bottles which all have stinging cells.
The tentacles of "true jellies" are armed with thousands of stinging cells. They feed the same way that jellyfish do. Some species have venom so strong that it is lethal to humans, such as the Autralian Box jelly which can kill a man in three minutes.
These juvenile moon jellies have been raised in the Two Oceans Aquarium's laboratory. They have the characteristic four leaf clover like pattern in their domes which easily identify the adults. They have short tentacles and are known as "mild" stingers.
The Threadfin Goldie
Also known as Fairy basslets. Widespread in the western Indian Ocean, south of KwaZulu-Natal. Forms dense shoals above coral reefs. Grows to 7cm.
Goldies are protogynous hermaphrodites. This means that they begin life as females and may later change sex to males. Goldies live in small to very large shoals. Within these shoals, dominant males, which are larger and more vibrant in colour, maintain harems of smalled females. Should a male be taken by a predator, the dominant female within his harem changes behaviour immediately to that of a male, taking his place before any of the others can do so. She becomes a functional male soon thereafter.
Comman near rocky reefs from False Bay to KwaZulu-Natal. Frequently taken by fisherman. Grows to 90cm.
(Diplodus sargus capensis)
One of the most common species. Occurs only along the east and south coasts of South Africa, from estuaries to offshore reefs. An omnivirous feeder. Grows to 60cm.
A common shoaling fish dound from Cape Agulhas to KwaZulu-Natal. Found on shallow offshore reefs and in estuaries. Feeds on midwater zooplankton. Grows to 25cm.
Big scale scorpionfish
Occurs at depths of 55-90m from Algoa Bay to KwaZulu-Natal. A common catch in trawl nets. Grows to 30cm.
An endemic species which occurs along the entire South African coastline. Commonly found in subtidal gullies and on shallow offshore reefs. Grows to 40cm.
Found only from Angola to KwaZulu-Natal over sand. Spwans close inshore. Caught with nets and lines at night. Juveniles utilise estuaries as nurseries. An economically important species of the Cape. Grows to 50cm.
An endemic species found from the Cape to KwaZulu-Natal. Common over shallow offshore reefs and in estuaries. Grows to 35cm.
Occurs along the entire South African coast. Found in sandy areas of estuaries and offshore down to 30m. Feeds on crustaceans and worms in sand. Grows to 55cm.
A Southern African endemic species. Occurs in tidal pools and sub-tidal gullies. Feeds on small invertebrates. Grows to 30cm.
A solitary fish found only in from False Bay to Maputo in depths of 20-200m. Grows to 60cm.
Occurs in large shoals on shallow offshore reefs and in estuaries from Cape Agulhas. Feeds on shrimps and other small invertebrates. Grows to 30cm.
A solitary and powerful predator which attains a weight of 45kg. Found only along the coasts of the Cape to KwaZulu-Natal on offshore, rocky reefs. Adults develop a large white fleshy "nose". A popular angling fish.
Feeds on phytoplankton. Caught by commercial netters.
Swims alone or in small groups over sandy areas. Feeds on worms, prawns and crabs. Grows to 75cm.
Feeds on fishes. An excellent commercial fish caught by trawlers. Makes bird-like chirping noises.
Found from Walvis bay to KwaZulu-Natal at gepths of 50-150m. Frequently caught by trawlers. Feeds on small crustaceans and worms. Grows to 35cm.
Found from Namibia to the Eastern Cape at depths of 10-150m. Feeds on small crustaceans.
Feeds on algae and benthic invertebrates.
Endemic to South Africa. This is the only butterflyfish, which is found along the entire South African coast. Found in tidal pools and on shallow reefs. Grows up to 15cm.
Exhibit #10 - Luminous light organs
Luminous light organs
The Pineapple fish has a pair of unique light organs on its lower jaw. This light is produced by a symbiotic bacterium. The fish provides the medium in its light organ for the bacterium to grow, and the bacterium produces the light as a by-product of its metabolism. The light is used for communication to confuse predators, and to see the small planktonic animals on which they prey.
This fish has lominescent light organs on its lower jaw. Occurs on inshore reefs off KwaZulu-Natal.
Exhibit #11 - The Reef Fringe (warm east coast)
The Reef fringe (warm east coast)
Fishes associated with inshore reefs along the east coast are quite different to those along the south coast. This is largely due to the difference in temperature in the two regions.
Generally, there are more species of fishes in warm waters and their colours are bright in comparison to the dull colours of the south coast.
Common throughout the Indo. West Pacific. Forms large tight shoals on shallow reefs, and in large tidal pools. Grows to 32cm.
Common throughout the indo-west Pacific. Reaches Algoa Bay. Feeds on crustaceans and small fishes. Grows to 14cm.
Occurs from Port Alfred northwards, in estuaries and on offshore reefs. Their venomous fin spines can cause painful wounds. Grows to 30cm.
Exhibit #12 - Soles and Tonguefishes
Soles and Tonguefishes
These falt fishes are adapted to life on the seabed where they lie concealed beneath a layer of sand and little more then their eyes exposed. They can change colour to closely match that of the sand by contracting and expanding different colour pigment cells in their skin. They eat worms and shellfish.
Common in False Bay, where it is frequently seen by divers over sand. Feeds by ingesting large amounts of sand, from which organic particules are extracted for nutrition.
Lives in shallow, sandy estuaries. Endemic to South Africa. Snout hooked. Tail fin.
Lives in estuaries and shallow sandy coastal areas on the east and south coast, where it feeds on small invertebrates. Its pectoral fin is black.
(Astropecten irregularis pontoporaeus)
Common on the Cape South Coast. Lives in sand, into which it digs in search of small molluscs and crustaceans.
Exhibit #13 - Pipefish
Occurs in tidal pools and among eelgrass in estuaries.
A close relative of the pipefish displayed here, the estuarine pipefish was recently thought to be extinct in the only estuaries where it had previously been recorded. However, a small population of these animals was recently rediscovered in an eastern cape estuary by researchers at the JLB Smith institute of Ichthyology in Grahamstown, who are now hoping to reintroduce this species into adjacent systems which have similar habitats.
Exhibit #14 - Shrimpfish
Shrimpfish drift head down, feeding on plankton. Their razor-like bodies are encased in bony plates and their small fins enable them to change direction with ease.
Exhibit #15 - Poisonous and Venomous Animals
Occurs on rocky reefs and over sandy areas as far south as P.E. Feeds on small invertebrates. Grows to 30cm.
Be warned by the bright colours of the venomous firefish. The spines inflict severe pain. They herd prey with their long fins.
Occurs from East London to KwaZulu-Natal on shallow rocky reefs. The venomous fin spines can cause painful wounds. Grows to 22cm.
Occurs throughout the Indo-Pacific. The venom, which is potentially fatal, is contained in the paired venom glands along each dorsal spine.
The most dangerous fish of all. The venom in the spines along its back is more deadly than that of a mamba.
Exhibit #16 - Seahorses and Anenomefish
Seahorses and kin
These strange little fishes with a mouths at the end of their snout include seahorses, pipefish and dragons. Their bodies are protected by bony plates arranged in rings. They occur in calm water and are propelled along slowly by their small fins. The males protect the eggs in a central pouch where the young then hatch and pop out into the water.
Seahorses hold onto eelgrass with their prehensile tails. The most common species is found in the Knysna estuaries.
Anenomefish have a certain relationship with anenomes: the fish benefit from the protection afforded by the anenome but the anenome is neither helped nor harmed. A coating of slime protects the anenomefish from the anenome stings. A family group of anenomefish includes a large dominant female, a smaller functional male, and several smaller stunted juveniles. If the female dies, the male changes sex to become a dominant female, and 1 of the juveniles develops into a reproductive male.
Exhibit #18 - Octopus
The octopus has 8 arms, each with two rows of suckers. It is a mollusc without a shell.
Exhibit #19 - Abalone or Perlemoen
Abalone are molluscs with a flattened, large muscular foot. They shed their sperm and eggs into the water and the larvae float briefly in the plankton. Juveniles live in sheltered places whereas the adults live on exposed reefs, especially in kelp forests. They feed on pieces of kelp or red algae which they hold down using their foot. Abalone breed at an age of 8-16 years and reach the minimum legal size (a diameter of 114mm) after about 13 years.
Exhibit #22 - Commercial Linefish
Swims alone or in small groups over sandy areas. Feeds on crabs, prawns and worms. Reaches 75cm.
Shoaling species found from the Cape to Kwazulu-Natal to depths of 100m on offshore reefs. Large shoals migrate up to Kwazulu-Natal and spawn during winter. Grows to 130cm.
Found over sand and rocky areas to depths of 80m.
A benthic predator found reaching depths of 100m.
Occurs from Cape to Kwazulu-Natal. Found in offshore reefs at a depth of about 80m. Feeds on fish. Grows to 75cm.
Likes shallow reefs just beyond the surf zone. Crushes perlemoen, crustaceans and redbait in its powerful jaws. Grows to 115cm.
(Pagellus bellottii natalensis)
Shaols of these fish are found over shallow, sandy areas.
Endemic species to South African waters. Found in shallow, rocky areas. Feeds on small invertebrates and kelp. Grows to 50cm.
Powerful predator found over deep reefs. Its liver is poisonous and has a high vitamin A content.
Frequently found in deeper reefs. Spawns in summer. Seldom caught from the shore.
An endemic species found only from Cape to Kwazulu-Natal. Caught in offshore reefs ???line boats down 2100m???. Grows to 75cm.
An endemic species found only in the Cape and Kwazulu-Natal in offshore reefs. Feeds on invertebrates and small fish. Grows to 75cm.
Widespread in the Atlantic and Indian ocean. Found on rocky ???shelfs and reefs. Excellent to commercial fish.
Important line and trawl fish found off South coast. Feeds on crustaceans, squid and fish. Spawns during summer.
Found around sandy areas and lagoons. It uses its elongated snout to feed on worms, prawns and crabs in sand. Grows to 200cm.
Endemic species found from Cape Town to Kwazulu-Natal. Found in large shoals over offshore reefs. Grows to 30cm.