STUDIES ON THE DlGBS'I1VE SYSTEM OF Stganus rivulatus WITH SPECIAL REFERENCE TO ITS FOOD AND FEEDING HABITS

STUDIES ON THE DlGBS’I1VE SYSTEM OF Stganus rivulatus WITH
SPECIAL REFERENCE TO ITS FOOD AND FEEDING HABITS
W. RIZKALLA·, F. I. AMIR·, F. I. EL – GAMMAL·· AND
M. Y. SHIEKH ELDIN·.
*Zoology DepertDent. Flculty of SCience. Ain-Shams University. Cliro.
**Nltional Institute of Oceanogrlphy and Fisheries. Red Sel and Suez Clnll
Branch. Suez. Egypt.
ABSTRACT
The gross anat~ of the dfgestfve syst.. of
st”nus rtvulatus shows that the llIOuth is of the
nibblfng type and there fs no sharp deMarcatfon
bet”,”n the buccil cavfty and phlrynx. thus fOl1llfng
the bucco-pharyngell clvfty. The oesophagus 1s I
long ..scular tube and leads to the fntestfnll bulb
as the stOMach fs absent fn thfs ffsh. The fntestfne
is long and c011ed.
The 1her 15 I dark brown organ wfth a broad
left lobe Ind I narrow rfght one. The pancrelS of
S. rtvulatus 11 of the ftdfss.fnlt.. and
fnterhepltfe..” type Ind the prfncfpal fslet fl
absent.
The lfnfng ..” of the buccopharyngell cavfty
fs fonned of IIUCOSI. IU_COSI and IIUscularfs. The
..cosa conlists of Itratiffed epfthelf… whfch
11 cCNlpOsed of polygonal cells. ..cus-Iecreting
celli with vlrfationl tn their s1ze Ind Ibundance.
taste budl and club-Ihaped celli whfch Ire conffned
only to the pharyngeal regfon. The ..scular1l fs
cCNlpOsed only of cfrcularly disposed Itrfated IIIlsc1e
fibers.
The lfnint ..11 of the oesophagul consfsts of
IlUCOII. lublllucosa. lIulcullrfs and serosa. The ..cosa
Is .de up of strlttfied epithe1f.. with n.-aroul
IIUCUS – lecretfng celli gtving the Ippearance Of
Itratfficatfon.
The ..” of the intestfnal bulb and fntestfne
proper (duodenllll. l1e.. and rect..) Is stlltlar to