pugnacity of the whale shark, rhincodon

Download Pugnacity of the Whale Shark, Rhincodon

Post on 07-Apr-2017

217 views

Category:

Documents

3 download

Embed Size (px)

TRANSCRIPT

  • Pugnacity of the Whale Shark, RhincodonAuthor(s): J. L. B. SmithSource: Copeia, Vol. 1967, No. 1 (Mar. 20, 1967), p. 237Published by: American Society of Ichthyologists and Herpetologists (ASIH)Stable URL: http://www.jstor.org/stable/1442210 .Accessed: 04/12/2014 20:26

    Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

    .JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact support@jstor.org.

    .

    American Society of Ichthyologists and Herpetologists (ASIH) is collaborating with JSTOR to digitize,preserve and extend access to Copeia.

    http://www.jstor.org

    This content downloaded from 169.230.243.252 on Thu, 4 Dec 2014 20:26:22 PMAll use subject to JSTOR Terms and Conditions

    http://www.jstor.org/action/showPublisher?publisherCode=asihhttp://www.jstor.org/stable/1442210?origin=JSTOR-pdfhttp://www.jstor.org/page/info/about/policies/terms.jsphttp://www.jstor.org/page/info/about/policies/terms.jsp

  • ICHTHYOLOGICAL NOTES ICHTHYOLOGICAL NOTES

    PUGNACITY OF THE WHALE SHARK, RHINCODON.-From its size alone the gi- gantic whale shark, Rhincodon typus Smith, always excites interest. It is so widespread and so often seen that it may appear surpris- ing that it was not described and named much earlier. This however had to await the coincidence of the stranding of a speci- men in reasonable condition where it could be examined and named by a competent scientist. This happened first at the Cape of Good Hope.

    The monotypic Rhincodon is perhaps most abundant in the western Indian Ocean; certainly it appears to be seen more often in that area than elsewhere. It appears to be particularly well known in the Mauritius- Seychelles area, where it is often seen from boats and by divers.

    As with large whales, the whale shark appears to be generally inoffensive, certainly all reports of its habits have stressed this character. Divers and people in small boats have repeatedly approached close to this animal in the surface without eliciting any hostile response. Generally, it appears that the whale shark has completely ignored them and even divers or swimmers who have touched or clambered on the animal while it was swimming. Fortunately this giant shark has not been exploited commercially, so that its obvious natural placidity does not appear to have been undermined by engendered fear of men and boats.

    It has therefore been all the more surpris- ing to receive a recent report of a different nature. Mr. J. Maurice Jauffret, noted angler and observer of marine life, of Port Louis, Mauritius, has written as follows: "As you are aware, RHINCODON TYPUS, the whale shark, is very common in our waters, and, whilst fishing, I have had many occasions to take my boat very close to them. They had showed no particular interest in the boat.

    "Since last year however, three fishing boats (cabin cruisers) belonging to members of our club have been attacked by these sharks whilst members of the crew were play- ing fish hooked in a shoal. Fortunately the boats sustained no damage. The last attack was made on my boat in which my son, Maurice, aged 23, was fishing. He reported that he saw the shark near a shoal of tunny, and whilst one of his friends was bringing in a 30 lb. fish, the monster (about 50 ft.

    PUGNACITY OF THE WHALE SHARK, RHINCODON.-From its size alone the gi- gantic whale shark, Rhincodon typus Smith, always excites interest. It is so widespread and so often seen that it may appear surpris- ing that it was not described and named much earlier. This however had to await the coincidence of the stranding of a speci- men in reasonable condition where it could be examined and named by a competent scientist. This happened first at the Cape of Good Hope.

    The monotypic Rhincodon is perhaps most abundant in the western Indian Ocean; certainly it appears to be seen more often in that area than elsewhere. It appears to be particularly well known in the Mauritius- Seychelles area, where it is often seen from boats and by divers.

    As with large whales, the whale shark appears to be generally inoffensive, certainly all reports of its habits have stressed this character. Divers and people in small boats have repeatedly approached close to this animal in the surface without eliciting any hostile response. Generally, it appears that the whale shark has completely ignored them and even divers or swimmers who have touched or clambered on the animal while it was swimming. Fortunately this giant shark has not been exploited commercially, so that its obvious natural placidity does not appear to have been undermined by engendered fear of men and boats.

    It has therefore been all the more surpris- ing to receive a recent report of a different nature. Mr. J. Maurice Jauffret, noted angler and observer of marine life, of Port Louis, Mauritius, has written as follows: "As you are aware, RHINCODON TYPUS, the whale shark, is very common in our waters, and, whilst fishing, I have had many occasions to take my boat very close to them. They had showed no particular interest in the boat.

    "Since last year however, three fishing boats (cabin cruisers) belonging to members of our club have been attacked by these sharks whilst members of the crew were play- ing fish hooked in a shoal. Fortunately the boats sustained no damage. The last attack was made on my boat in which my son, Maurice, aged 23, was fishing. He reported that he saw the shark near a shoal of tunny, and whilst one of his friends was bringing in a 30 lb. fish, the monster (about 50 ft.

    long) raised his head out of the water and came straight for the boat. He hit the boat astern and turned her right round. The shock was so hard that all the crew were thrown down. My son then put the engine in full throttle and the shark did not fol- low."

    In response to queries Mr. Jauffret has assured me that there is no question of the identity of at least the shark that attacked his launch. From long experience he and others mentioned know this shark well and they clearly saw on this particular animal the light markings characteristic of the species.

    It is significant that the circumstances of attack in all the cases reported by Mr. Jauffret were identical. Each attack was directed at a boat in which an angler was playing a large fish hooked from a shoal.

    J. L. B. SMITH, Rhodes University, Grahams- town, South Africa.

    REDUCTION IN BRANCHIOSTEGAL RAY NUMBER.-Hubbs (1919) has pub- lished virtually the only comparative study of teleostean branchiostegal rays. Recently Dr. D. E. McAllister has presented the results of a much more extensive study of the subject in a Ph.D. thesis which is now in press. Drs. McAllister and D. M. Cohen have been kind enough to offer suggestions that have been incorporated in the present note.

    Hubbs (1919) showed that among teleosts there tends to be a large though variable number (usually 10-20) branchiostegal rays in lower forms, whereas acanthopterans al- most never have more than eight. Time after time, however, this evolutionary ten- dency for gradual reduction in number is

    abruptly short-circuited to four or even fewer rays. The present note will attempt to show that many instances of this sort have a functional explanation.

    The milkfish, Chanos chanos, with four branchiostegals, is an example. Chanos (Fig. lc, d) is a small-mouthed fish, and its man- dibular articulation, as compared with the more usual condition exemplified by Elops (Fig. la, b), has moved far forward. In association with this, the quadrate of Chanos has become anteriorly displaced and has lost the normal contact not only with the from the posterior end of the symplectic to

    long) raised his head out of the water and came straight for the boat. He hit the boat astern and turned her right round. The shock was so hard that all the crew were thrown down. My son then put the engine in full throttle and the shark did not fol- low."

    In response to queries Mr. Jauffret has assured me that there is no question of the identity of at least the shark that attacked his launch. From long experience he and others mentioned know this shark well and they clearly saw on this particular animal the light markings characteristic of the species.

    It is significant that the circumstances of attack in all the cases reported by Mr. Jauffret were identical. Each attack was directed at a boat in which an angler was playing a large fish hooked from a shoal.

    J. L. B. SMITH, Rhodes University, Grahams- town, South Africa.

    REDUCTION IN BRANCHIOSTEGAL RAY NUMBER.-Hubbs (1919) has pub- lished virtually the only comparative study of teleostean branchiostegal rays. Recently Dr. D. E. McAllister has presented the results of a much more extensive study of the subject in a Ph.D. thesis which is now in press. Drs. McAllister and D. M. Cohen have been kind enough to offer suggestions that have been incorporated in the present note.

    Hubbs (1919) showed that among teleosts there tends to be a large though variable number (usually 10-20) branchiostegal rays in lower forms, whereas acanthopterans al- most never have more than eight. Time after time, however, this evolutionary ten- dency for gradual reduction in number is

    abruptly short-circuited to four or even fewer rays. The present note will attempt to show that many instances of this sort have a functional explanation.

    The milkfish, Chanos chanos, with four branchiostegals, is an example. Chanos (Fig. lc, d) is a

Recommended

View more >