• Welcome to ScubaBoard

  1. Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

    Benefits of registering include

    • Ability to post and comment on topics and discussions.
    • A Free photo gallery to share your dive photos with the world.
    • You can make this box go away

    Joining is quick and easy. Login or Register now by clicking on the button

Shark Education Thread!

Discussion in 'Shark Forum!' started by gcbryan, Jun 25, 2010.

  1. gcbryan

    gcbryan One Bad Hombre

    # of Dives: 1,000 - 2,499
    Location: Seattle
    16,095
    10,102
    113
    How about giving us some info regarding your favorite shark.

    For me it's the Pacific Bluntnose Sixgill shark. I've had 29 encounters and therefore have been able to observe it at length.

    It's unusual in that it has 6 gill slits (rather than the more "modern" 5 gill slits) and it has a different pattern/type of teeth from lower to upper jaw. The upper teeth are pointy and are the 'grabbers" and the lower teeth are of the grinding/cutting variety. In many sharks both sets of teeth (upper and lower) are the same.

    Girth is the most impressive aspect of this shark once you encounter a specimen longer than 8 feet. The beautiful green eyes are immediately noticeable as well.

    The sixgill has a proportionally (very) large tail and although it has a dorsal fin it's small and located closer to the rear of the spine.

    They have no iris and therefore no way of regulating incoming light. They are bottom feeders as well as opportunistic feeders. Located in all of the worlds oceans this is generally a deep water shark and isn't commonly at the same depths as divers. There are exceptions and the PNW is one of those exceptions.

    The reasons aren't entirely known but there is little difference in temperature between our surface waters and the oceans bottom temp. Due to all of the nutrients in our waters visibility is limited (dark) and this could account for bringing them to shallower waters as well.

    The main difference is probably our unique setting inland (90 miles) from the open ocean. In the years when there are more sightings it's believed that they are using Puget Sound as a nursery. Sexual maturity isn't until they are in the 10-12 foot range and sixgills much past the 12 foot range aren't generally encountered here.

    This is generally a slow (relatively speaking) shark that when encountered may swim circles around the diver and it's not unusual for them to swim directly under the diver (I don't generally let them swim directly over me).

    You can sometimes find smaller sixgills laying on the bottom resting. They don't appear to be aggressive but I'm sure that's more in the vein that a families pet lab isn't generally aggressive but you still shouldn't hit it or take its food! This is a large shark with very impressive teeth.

    They do have relatively weak connective tissue joining the jaws compared to many other sharks. This can break if catch and release is allowed. I encountered such a shark once. Its mouth was permanently open...this was a bit disconcerting until I figured out what was going on!

    They can move rapidly. I saw a smaller 5 foot sixgill at midnight on one occasion moving as rapidly as the smallest dogfish darting about. This was also the exception to allowing a shark to swim directly over me.

    I've seen the skin of a sixgill at our local aquarium and it feels like sandpaper. In the water on a live specimen it doesn't feel like that (to me). It feels like firm plastic.

    Due to their large size, their lethargic movements betray their actual speed. One slow move of their tail and it's easy for a diver to not be able to catch up when they are ready to leave and yet they don't appears to be moving rapidly at all.

    Around here, during the years when they are most viewable, it's mainly a dusk to dawn sighting at 100 fsw or deeper. They have been sighted up to about 10 am and as the night progresses they do get shallower.

    I've seen one at 35 fsw. Most have been 100 fsw - 120 fsw shortly after dusk. When they were around more I saw them in most every month of the year but the larger sharks and the more frequent sightings were in spring and fall.

    I think the larger sharks (still immature) were moving around seasonally in our inland waters (including Canadian waters). Once they actually mature and go back to the open oceans I don't think we ever see those again. The actually breeding may not even be done here.

    My most memorable sighting was two 10' sixgills simultaneously passing at right angles to us (and each other). It's a strange feeling to have to pick one to follow while turning your back on the other 10' shark!

    This is the Shark Forum. There must be other shark enthusiasts here. Tell us about the shark that you know the most about!
     
  2. SharkSafaris

    SharkSafaris Angel Fish

    # of Dives:
    Location: Southern Africa
    17
    0
    0
    All shark species are my favorite shark although the broadnosed sevengill shark (also called cow shark) Notorynchus cepedianus is one I have quite some experience with. Some 200 dives with this now and I started to think of them individually. I'll drop some info on them later, but right now I'm in a hurry to get out and dive with them :wink:
     
  3. Go Bear Grylls

    Go Bear Grylls Garibaldi

    3
    0
    0
    I am a fan of Man Vs. Wild idk if anyone here is anyway...He had a new episode last night and he was in the Pacific ocean between Australia and Papua New Guinea. He tries to get in the water but sharks are everywhere. I must know what type of shark this is...anyone? This is a link to the video clip on the discovery website. i had to replace the .com with a dot com so that i could post this. so you will have to change that in this link for it to work

    dsc.discovery dot com/videos/man-vs-wild-western-pacific/

    thanks
    -Go Bear Grylls
     
  4. Go Bear Grylls

    Go Bear Grylls Garibaldi

    3
    0
    0
    This forum is dead and gone. Its an old sleepy ghost town. Nobody is here to answer anything man what a waste of a domain.

    Go bear grylls
     
  5. LIVES4SHARKS

    LIVES4SHARKS SHARK DIVA AI ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Savannah, Georgia
    4,823
    58
    0
    Hey GBG, sorry no one has responded to ya. The Shark in question is the White Tip Reef Shark. They tend to stay on the bottom and feed at night. http://en.wikipedia.org/wiki/Whitetip_reef_shark

    [​IMG]

    They are also known for their singing abilities. :wink:



    Carolyn:shark2:
     
  6. Go Bear Grylls

    Go Bear Grylls Garibaldi

    3
    0
    0
    thanks so much yer right it looks just like them. lol and the singing is just amazing! haha what are they really doing down there?
     
  7. LIVES4SHARKS

    LIVES4SHARKS SHARK DIVA AI ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Savannah, Georgia
    4,823
    58
    0
    Like similiar bottom dwelling sharks (nurse sharks), they just tend to hang out on the bottom. Since they aren't swimming to breathe, they just breathe like you see in the video, kind of like "gulping", forcing water through their gills.

    Carolyn:shark2:
     
    Last edited: Sep 9, 2010
  8. JDiver56

    JDiver56 Angel Fish

    # of Dives:
    Location: NorCal
    17
    2
    0
    I tend to favor silvertips Carcharhinus albimarginatus) - I don't know, they just seem like a "shark's shark" to me, and I've seen whitetips, blacktips, grey whalers / reefies etc. give way to them.

    [​IMG]
    (From DeepSeaImages.com)
     
  9. drbill

    drbill The Lorax for the Kelp Forest Scuba Legend

    # of Dives: 2,500 - 4,999
    Location: Santa Catalina Island, CA
    22,446
    5,315
    113
    I like soupfins since they look like they could be dangerous but are actually afraid of our bubbles. Makes them more challenging to film. Great whites are also hiugh on my list, but I've only filmed them from a cage off Guadalupe (the one I know swam past me was chicken... it swam behind me as I was filming giant sea bass but dive buddy Wyland saw it).
     

Share This Page