Suspicious shark sighting - what was it up to?

[smellzlikefish]

...which is the entire reasoning behind using scientific names. There's no mistaking C. melanopterus and C. limbatus, yet they are both completely unrelated blacktips. In truth, I have heard C. melanopterus (blacktip reef shark) referred to as "blacktips" more than I've heard C. limbatus (blacktip shark) referred to as "blacktips." What Aussies call grey nurses, east coast Americans call sand tigers, and unless you hang around the pelagios a lot, a whitetip is probably a whitetip reef shark. It is simply a matter of what your background is, which is the whole problem with common names. They confuse EVERYONE.

I've seen sand tigers resting and it wasn't because they were healthy. Some causes include not enough fishy oil in the liver, bacterial infection, and stress. I have heard of them resting in grooves in spur and grooves in the reef. I believe the smalltooth sandtiger that was seen on Oahu was resting when it was found.

As for the whitetip cleaning, do a literature search for Cleaner host posing behavior of whitetip reef sharks in a swarm of hyperiid amphipods. The sharks were doing something very similar. In fact, if you look closely, you'll often find cleaners in the caves that whitetip reef sharks frequent.

 

[MauiScubaSteve]

http://www.scubaboard.com/forums/hawaii-ohana/242046-white-tip-reef-shark-mouth-cleaning.html

If you look at the linked thread, the pictures and video are just inside the mouth of a "dead end" cave that has very little "surge" where the images are shot and pretty much no current. The area in those images is a cleaning station,

In fact, if you look closely, you'll often find cleaners in the caves that whitetip reef sharks frequent.

Fair enough and not clearly implied earlier. This kind of Hawaiian cleaner wrasse inside mouth cleaning has not been observed often to my knowledge, especially deeper in this cave system.

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[DiveTheGalapagos]

In the Galapagos, you see white-tipped reef sharks on pretty much every dive in the east central islands. I see them resting more than swimming actually. It's normal. There are even tourist sites set up for people to walk on land and see them at designated overviews...canals where they come to rest during the day. In addition to seeing them when diving, there are various places you can go snorkel where they rest in shallow water and usually in groups of at least 12.

As I understand it, Scubahagel nailed it ... they usually rest in places with enough current to keep the water flowing over their gills without movement.