In this publication I will explain what is a submarine canyon and, in concret, I will give some details from the submarine canyon of Cap de Creus, in Catalonia.
WHAT IS A SUBMARINE CANYON?
A submarine canyon is a valley placed in the continental platform, formed when the sea level was lower.
SUBMARINE CANYON OF CAP DE CREUS
The submarine canyon of Cap de Creus is 3 km to the coast and it has a length of 40 km and the hightest depth is 1400 m. In the next picture, at the left side we can watch a 2D image of its place and the first part of this canyon, meanwhile in the right side we can see the same part in 3D. Both picture have been obteined with the program ArcGis.
The canyon has a high diversity. The communities presents at 190 metres are very different from the observed at the continental platform. The most characteristic specie is the scleractinian coral Madrepora oculata, a white coral from depths and cold waters, very important for benthic animals and young fishes. For this reason, the experts request for their protection and conservation.
The goal of this publication is to describe the different cetaceans that live in the catalan coast. At first, I will explain you what is a cetacean and then I will describe them.
Cetaceans are a mammal order that live adapted to swimming and, for this reason, they develop all the activities in the water. Most of them live in the sea, but there are a small group that live in fresh water. This adaptation consists on the presence of hydrodynamic bodies to reduce the resistance and the presence of fins (pectorals, dorsal and caudal fins). Cetaceans, as well as the rest of the mammals, are homeotherms (they have physiological mechanisms to keep a constant temperature of the body, known as warm-blooded). Furthermore, they breath air and, for this reason, their nostrils are dorsal, called blowhole. More or less, there are 80 species of cetaceans, subdivided on: odontoceti (toothed cetaceans, which includes dolphins, porpoises, beluga, narwhal, beaked whales and sperm whales) and mysticti (cetaceans without teeth; which includes whales and fin whales).
8 species live in the coast of Catalonia: common bottlenose dolphin, short-beaked common dolphin, striped dolphin, fin whale, sperm whale, Risso’s dolphin, long-finned pilot whale and Cuvier’s beaked whale.
COMMON BOTTLENOSE DOLPHIN
Common bottlenose dolphin (Tursiops truncatus) is the most typical dolphin in zoos. We can recognise them for the color of their skin: mainly is grey, but the abdomen is lighter. The dorsal fin is convex. This dolphins usually live in groups of 2 – 15 individuals, but sometimes the groups are composed for several hundreds. They are very acrobatic. Common bottlenose dolphin has the global conservation status of “least concern”, but in the Mediterranean Sea is “vulnerable” (UICN).
SHORT-BEAKED COMMON DOLPHIN
Short-beaked common dolphin (Delphinus delphis) is easily recognisable for the color patron. Its back is grey or brown with a V drawing under the dorsal fin. In addition, they have a yellowish patch and a grey patch in the sides that form a typical hourglasse figure. They usually live in groups of 10 – 200 individuals. Like, common bottlenose dolphins, they are good acrobats. They are endangered in the Mediterranean Sea, but in global their category from UICN is “least concern”.
Striped dolphins (Stenella coeruleoalba) have a brown or grey dorsal fin, moderately high; dark and prominent beak, well distinguished from the melon (a lump of fatty tissue that forms the forehead of toothed whales and tht is thought to function as a means of focusing sound for echolocation); and its back is grey or brown, light grey from the center of each side to dorsal fin and in the subsequent part. Moreover, they have a thin dark line from the beak to the lower part of sides. They normally live in groups of 25 – 100 individuals. They are good acrobats too. Striped dolphin is the most abundant cetacean in the North West of the Mediterranean Sea, but its status is vulnerable here.
Fin whale (Balaenoptera physalus) is the biggest cetacean of the catalan coast. Fin whales have a high dorsal fin, placed at last third of the body and a wide and flattened head. Their body is long and dark grey without spots, more lighter in the abdomen. You can’t usually see their caudal fin. Their conservation status is “vulnerable” in de Mediterranean Sea, but is “endangered” in global.
Sperm whale (Physeter macrocephalus) is another big cetacean in Mediterranean Sea. The lobes of the tail are wide and triangular, with an important groove; they have an small hump, followed for six protuberances; their head is rounded and represent one third of the body; and their body color is dark grey to brown violet. Their blast is leaning and place a little in the left. They usually swim slowly. Spearm whale is catalogued as “vulnerable” in global for UICN, but in the Mediterranean is “endangered”.
Risso’s dolphin (Grampus griseus), known like grey dolphin too, has a high dorsal fin, long sharp pectoral fins, a rounded head with a bulbous melon, a curved mouth and a grey to brown color, with several marks and lighter abdomen. They usually live in groups of 3 – 30 individuals, but sometimes they live in groups of several miles. Their conservation status is “least concern” in general, but there isn’t enough information for Mediterranean.
LONG-FINNED PILOT WHALE
Long-finned pilot whale (Globicephala melas) has a short, wide rounded dorsal fin; high and narrow pectoral fins that mesure a fifth part of the body; a bulbous melon; a short snout; and the color of its body is dark grey, black or brown. They normally live in groups of 10 – 60 individuals. There isn’t enough information to evaluate their conservation status.
CUVIER’S BEAKED WHALE
Cuvier’s beaked whale (Ziphius cavirostris) is a species with a little surface activity and for this reason is very hard to see it. Its caudal fin has wide lobes, without a central groove or very small and lightly sickle-shaped. The dorsal fin is placed behind the center of the body. The snout is short, curved and cream-coloured. The color of the body is brown reddish to dark grey, with darker abdomen. They usually live in groups of 2 – 7 members, ocasionally untill 25, but older males normally live alone. There isn’t enough information to evaluate their conservation status.
This are the 8 most tipical species in the coast of Catalonia. I hope that with this small guide you could identify them easily.