Whitetip Reef Sharks – The Dark Knight of Cocos Island

Photo courtesy from The Great Fiji Shark Count

Whitetip Reef Shark (Triaenodon obesus)

Max. Length: 213 centimeters
Length at 1^st Maturity: 104.5 centimeters
Weight: 30 kilograms
a value: 0.00180
b value: 3.344
Depth Range: 1 – 330 meters but usually at 8 – 40 meters
Frequency: Near threatened due to high demand in shark’s fin

If we are to give you the easiest way to identify this type of shark, then it should be the white shading at the tip of its dorsal fin. This small and slender shark has a gray colored body with a white undertone on its belly and sometimes with dark spots on the side. They have a short and broad snout, eyes that are oval and jaws that have at least 47 – 50 teeth in each jaw scattered in 2 functional dental layers.

Your Usual Interaction at Cocos Island

Before you can make any interaction with the signature species of Cocos island which are the hammerhead sharks, you will first interact with the Whitetip Reef Sharks.

Photo courtesy from Khao Lak Explorer

During your day dive in some of the top diving sites of Cocos Island, you will usually start by entering a shallow water environment going to the reef ledge where you can see the big boys of the deep being pampered in a cleaning station. During you traverse in the reef, you will notice that whitetip tip reef sharks occupies the ground portions of the reef either swimming in a gentle pattern or lying motionless in the bottom.

But you may wonder: Why whitetip reef sharks are usually resting on the ground during the day? If you want to find out the cause of their sluggish behavior from the onset of sunrise up to sunset, then you should go diving with them in the dark.

Night diving with Whitetip Reef Sharks

Photo courtesy from www.raydiving.com

When sunlight is about to retreat, especially in the reefs of Manuelita, whitetip reef sharks will rise up from a days long rest and start to become active in search for food. When you go night diving in a spot called Manuelita Inside, you will be greeted by fast moving whitetip sharks once you enter the water.

Given the fact that this is a night dive and an underwater torch is a mandatory equipment, you will notice that the beam produced from your lighting system will further agitate the behavior of these sharks. If food (like crabs, squids and small fish) is nearby and available, these sharks may shift in to a feeding frenzy mode where several sharks compete to get the biggest share of the night.

After several hours of active life and the sun is about to show its might, these sharks returns back to their rest mode and the cycle repeats itself when night time comes again.

Reef species are different from Oceanic Patrollers

An Oceanic Whitetip Shark. Photo courtesy from www.requins.eu

Be reminded that Whitetip reef sharks are different from Oceanic Whitetip (Carcharhinus longimanus). Although both species exhibit the very basic identification mark which is the whitetip marking on the tip of the dorsal fin, there are several differences between these sharks. First, a whitetip reef shark poses no threat to humans while Oceanic Whitetips are relatively aggressive to humans. Second, in terms of body feature, the Oceanic species are more bigger than its reef cousins and the snout of an Oceanic whitetip are rounded compared to the broad and short size of a whitetip reef shark.

Finally, look in to the eyes where an oceanic whitetip’s eyes are circular compared to the oval shape eyes of its reef cousins.

Reference

Fishbase: www.fishbase.org

IUCN Redlist of Threatened Species: www.iucnredlist.org

Marine Bio: www.marinebio.org

Video courtesy from Sandy Jadresko

About Tristan Paylado
Tristan is a marine biologist and a CMAS 2-Star Dive Instructor
View all posts by Tristan Paylado →