O`ahu. 30 ft.
Canthigaster jactator (Jenkins, 1901)
Tobies, sometimes called "sharpnose
pufferfish" are diminutive puffers with a somewhat elongated
snout. They are generally less than 4 inches long and constitute a
subfamily within the larger pufferfish family, Tetraodontidae. Out
of five species of tobies in Hawai`i, this is by far the most common.
It is brown with white spots. The eye is green and the body often
displays a slight green fluorescence. Usually in pairs, these fish
occur on hard substrate just about everywhere, both in areas of 100%
coral cover and in dead silty places where little else seems to live.
Some individuals have irregular black marks on the snout, body, and
finsperhaps a disease. Others are so distended with parasitic
worms (nematodes) that they appear inflated. One study indicated that
Hawaiian Whitespotted Tobies feed mostly on green and red algae; another
showed sponges to be the main food, followed by algae and tunicates.
Aquarists have observed these cute but mischievous puffers stealthily
approaching other fishes and nipping their fins, leaving perfect semicircular
"cookie-bites" along the edges. They also nip at the skin
of resting sea turtles, especially those with tumorous growths, causing
the turtles to flinch. The species name means "boaster,"
or "braggart," no doubt because of the fishs ability
to inflate. It attains about 3.5 inches and is endemic to the Hawaiian
Islands. Two similar sister species exist, C. janthinoptera
in the Indo-Pacific (excluding Hawai`i) and C. punctatissima
in the Eastern Pacific, both with smaller white spots.
Black marks -
Magic Island, O`ahu. 20 ft.
Distended by nematode worms - Marty's Reef, South Maui, 50 ft
ORGANIZATION AND LIFESTYLE
Although the Hawaiian species has
not been studied in detail, the similar Eastern Pacific White-Spotted
Toby, Canthigaster punctatissima, has been found to be sexually
dimorphic (males larger than females) with both sexes defending
territories against others of their own sex. Male territories include
the smaller territories of one to four females. The male pairs with
each of his females at different times and his females never pair
with other males. If a male is removed, his territory is absorbed
into that of a neighboring male, often overnight. The lifestyle
of C. jactator is likely similar, as demonstrated by a very
small study performed in 1985 by high
school students Kim Bruno and Marguerite Nogues.
During 5 scuba dives, Bruno and Nogues
observed that the little puffers spent most of their time in pairs
(although not necessarily next to or very near each other) and swam
in a distinct pattern which seemed to mark circular territories
that varied in diameter from three to twenty feet. (The students
marked the territory boundaries with nails and observed that the
tobies were curious, often inspecting these shiny foreign objects.)
On one occasion a toby entered another pairs area and one
of the resident tobies swam out, nipped its side, and chased it
away, indicating defense of a territory. The tobies spent about
50 percent of the daytime time swimming around the territory, 40
percent hiding among the rocks, and about 10 percent feeding.
What do they do at night? We don't
know much, but Wiilliam J. Walsh, while studying fish sheltering
behavior in Kona, noted that a Hawaiian Whitespotted Toby rested
at night on one of his polypropylene transect lines spanning a vertical
wall. Although the line was essentially the same thoughout its length,
the toby rested each night within an inch of the same precise spot
for a period of over two weeks.
Diving at Mäkua, O`ahu, photographer
David R. Schrichte watched a pair of Canthigaster jactator
apparently spawning. The fish on the right (presumably the male) pursued
the fish with the swollen belly on the left (presumably the female)
into a hole (photo #1). The swollen fish positioned itself repeatedly
in a particular spot and trembled as if it were laying eggs (photo
#2). A photo of a totally different pair at Kahe Point, O`ahu, seems
to show a male (right) fertilizing eggs just laid by a still swollen
female (photo #3).
1 - About to spawn? Photo
copyright David R. Schrichte
2 - Laying eggs?
- Photo copyright David R. Schrichte
3 - Male (in back)
Observing a Whitespotted Toby under
ultraviolet light, University of Hawai`i researcher Jill P. Zamzow
discovered some subtle spots on the fish that were visible only when
its mucus was wiped off. The mucus was apparently blocking the ultraviolet
light from her lamp. In nature, she surmised, UV-absorbing compounds
in the mucus probably protect the fish from the suns damaging
radiation. The UV-blocking capability of Whitespotted Toby mucus turned
out to be equal in strength to SPF 15 human sunscreen. Intrigued,
Zamzow examined the mucus of 200 other Indo-Pacific reef fishes, finding
sunscreen compounds in 84 percent of them. One, the Hawaiian Saddle
Wrasse (Thalassoma duperrey), was even able to change the SPF
factor of its mucus depending upon the depth at which it lived.