The largest living fish, the whale shark (Rhincodon typus) is a huge carpet shark which cruises through tropical oceans around the world, feeding on plankton and small fish. On average, whale sharks reach 10 metres in length and weigh around 10 tonnes, however, the largest specimen discovered weighed 21.5 tonnes and was 12.65 metres in length (the equivalent weight and length of a fully-loaded bus)! They are grey in colour with a white belly; each individual also has a unique pattern of white spots. Like most sharks, they have two pectoral fins (side-fins) and two dorsal fins (back-fins).
The whale shark is a truly phenomenal animal and despite their size and intimidating name, they do not pose a threat to us. Rather, they prefer to use their 1.5 metre wide mouth to trap and digest colossal amounts of plankton as they glide through the ocean. They will also feed on clouds of eggs during the mass spawning of fish and corals. Impressively, their mouth can contain up to 350 rows of tiny teeth yet these teeth play no part in the whale shark’s feeding routine – they have become vestigial teeth over the course of evolution.
Unfortunately, this mighty fish is listed as endangered by the IUCN. One of the reasons for this is because hundreds of whale sharks are illegally slaughtered in China every year for their skins, oils and fins; they are also frequently hunted in the Philippines. Additionally, they are threatened by the impacts of fisheries, by-catch losses which reduce their availability of prey, and vessel strikes. Their gestation period is unknown, but their long life-span and late maturation mean that it will be difficult to raise their population numbers.
The whale shark’s huge size, combined with its docile nature and elegance make it almost a ‘shark of contrasts’, and it is this uniqueness which means we should help to protect them. Still very little is known about this species’ reproduction and breeding habits since neither the mating nor pupping of whale sharks has ever been documented, making their conservation all the more necessary.
With its large, venomous spines and vibrant striped pattern, the red lionfish (Pterois volitans) appears to be a very intimidating animal. This particular species is one of the largest lionfish species in the ocean; they are distributed throughout the Indo-pacific ocean region. However, they have been introduced to the West Atlantic which has led to an invasive problem.
The red lionfish is a night hunter whereby they often stalk their prey and pounce upon them at lightning speed, similar to a terrestrial lion hunting in the African plains. Their diet consists of small fish and crustaceans found across the coral and rocky reefs of the ocean.
This fish is wonderfully adapted to its reef environment with large eyes to help them see in dim light and an acute sense of smell. Moreover, their fleshy ‘whiskers’ help to disguise the lionfish’s open mouth when approaching prey. They have large venomous spines in their dorsal, anal and pelvic fins which help deter potential predators and these thin spines resemble a mane – another parallel to the African lion, hence the name ‘lionfish’. However, due to their threatening appearance and lack of predators, their populations have grown massively (especially in the Caribbean) which has damaged local ecosystems and food chains.
A few years ago, whilst I was on holiday in Egypt, I was lucky enough to visit the red sea and I saw countless red lionfish swimming alarmingly close to me. I was aware of their venomous spines so I knew to stay away even though their spines are used purely for defence. Whilst you’re alone in the ocean with these bright red fish you are able to see how menacing that vibrant pattern is; their warning stripes are definitely enough to deter any predators.
Sadly, these magnificent creatures are becoming a danger to fragile ecosystems in the Caribbean and the eastern coast of the USA due to humans introducing these fish into the West Atlantic. As an exceptionally skilled hunter, the red lionfish easily out-competes native fish species and this, along with their varied diet, is drastically disrupting marine ecosystems, leading to a reduction in marine biodiversity.
The giant oceanic manta ray (Manta birostris) is the largest species of ray in the world. This huge fish can grow up to 7 metres across, dwarfing any nearby diver. They are distributed globally around the equator, found in tropical and subtropical waters, and their magnificent beauty is unmatched.
I was lucky enough to see a manta ray whilst I was in Tobago in the Caribbean. My brother and I were looking down into the sea when we saw this large, greyish-black object moving steadily through the water. At first, we thought it was a rock but then we wondered ‘why is the rock moving?’. Once I saw those iconic cephalic fins at the front of its head (which are forward extensions of their pectoral fins) I knew it was a manta ray.
Manta rays are filter feeders, they use these cephalic fins to funnel zooplankton (mainly shrimp, krill, and planktonic crabs) into its mouth as it travels through the ocean. They are often accompanied by small cleaner fish which consume bits of dead skin and parasites lying on the manta’s smooth skin; they have a nice symbiotic relationship with one another. The manta ray’s stay free of parasites and disease whilst the cleaner fish get a nutritious meal.
I adore the colossal size and elegance of this species. However, they are listed as vulnerable by the IUCN (International Union for Conservation of Nature) and they are threatened by human activity, particularly fishing. Sadly, it is often the youngest manta rays which are caught and killed in the fishing nets – their cephalic lobes become easily entangled in nets. This is especially damaging to this species because manta rays have a 13 month gestation period and only birth one pup at a time meaning it is difficult to maintain their population, and this struggle will only increase as the demand for fishing industries grows.
The manta ray is an exceptionally unique species which deserves our protection.