A Comparative Study of the Feeding Mechanisms of

some AFrican (Pisces, )

by

H. Matthes

Zoological Laboratory, University of Amsterdam

with 12 plates

there voluminous litera- Vincig., Xenobarhus Although exists an extremely namely: Phreatichthys 1924,

Caecobarbus ture on Cyprinid fishes and the morphology and phy- Norman, 1923, and Blgr., 1921, only

of has the last has had with siology some species been intensively studied its biology investigated, though

little known about reference its habits and by various authors, very is yet no special to feeding morpho- derived feeding mechanisms and their functioning in most logy (Heuts, 1951), and all are directly from members of this family. , from which they apparently differ little. A-

So far ￿ non-African as known, only some European species mongst species, Cyprinus carpio Linn., and Rasbora e-g- Cyprinus carpio, Carassius auratus, iRutihis ruti- 1758, Leuciscus cephalus (Linn., 1758)

Gobio ￿ and also for lus, gobio one Asian (Labeo rohita), one sp. were examined, comparative purposes. African (Labeo horie) have been investigated thor- The bulk of the ecological data stems from personal

in in in oughly as regards their morphology relation to observations on live fish, either nature or aqua-

their habits. of well from feeding Moreover ,the ecology most ria, as as numerous gut content analyses. African culled species is only scantily known. Complementary information was from various This of the mechanisms study feeding of one or sources, e.g. Girgis (1952), Greenwood (1958),

of of the African Fryer Daget Poll more typical representatives most (1959), (1954), (1953; 1959),

genera, will, I hope, serve to clarify some interesting Boulenger (1901; 1907), etc. The osteology and

and lead lines of field musculature of the mouth and studied points to new research in a pharynx were

where so much is still left to be done. from mounted skeletons, Alizarin preparations (for

small species) and from careful dissections (also under ACKNOWLEDGEMENTS the microscope).

For material of African A series of bones from both Afri- generous help in providing large pharyngeal well facilities and also and Cyprinidae as as working at the "Mus￿e can European species was examined

Royal d'Afrique Centrale" (Tervuren), I'm deeply in- compared.

The nomenclature depted to Prof. M. Poll, conservator of vertebrates followed is essentially the same

there. thanks also for that used My the help received from Prof. as by Gregory (1933) and Ramaswami

Dr. E. under whose this work for the bones and Edge for J. Slijper, guidance (1955) by worth (1935)

carried and his the muscles. the was out, to assistants at the "Zo~lo- Owing to fact that muscle nomen-

Amsterdam I'm also clature found to be rather table of the gisch Laboratorium", University. was confused, a thankful cranial muscles very to Prof. Dr. H. Engel, director of the and their main function has been

drawn "Zoologisch Museum" (Amsterdam), who kindly al- up (Table I) enabling rapid comparison of the lowed the full of the of the different used authors. me use library Ichthyolo- names by various No attempt

gy section. at establishing synonymies for these different terms

made. The used in was names this paper are the

MATERIALS AND METHODS which ones appear most appropriate, taking into ac- the Species belonging to following genera were taken count not only the muscle function but also its onto-

under consideration: geny.

Labeo, Garra, Barbus, Varicorhinus, Barbopsis, In order to study the finer structure of the inner

Coptostomabarb us, Leptocypris, Barilius, Engraulicy- mouth and pharyngeal linings, histological sections of

head pris, Chelaethiops. the region of Barbus pleuropholis and of the

Of the three other African not studied lamellar genera here, vomero-palatine organ and pharyngeal pad 4 H. MATTHES

Labeo lineatus made. the maxillaries excluded from ("palatal organ") of were Stain- only, being completely

done with and the of the mouth. and barbels various- ing was mostly Azan Haematoxylin- gape Lips are absent Eosin. Numerous drawings and photographs have ly developed and may even be altogether.

all salient Paired valvular been included in order to illustrate points. nostrils, separated by a flap, are si-

tuated the the the of on snout, anterior to eye; sense

smell is known to be well developed in GENERAL INTRODUCTION extremely 1957, vol. II). The form rich and diversi- Cyprinids (Brown, Cyprinidae an extremely A membraneous valve is present along the inner fied family and its numerous species have adapted to side of the valve). A true This di- upper jaw only (maxillary a broad variety of environments. ecological remarkable devel- tongue is, with one exception, not versity is directly related to their high morphological

oped, there a more or less ,and remarkable only appearing distinctly variability many trophic specialisa- raised hump in the mouth-floor, over the glossohyal. tions illustrate the close relationship between the The inner lining of the bucco-pharyngeal cavity morphology of their feeding mechanisms and their gen-

numerous more or less mode of life. erally presents longitudinal and the be modified in be subdivided plicae palatal epithelium may Feeding in Cyprinids can into sever- several relation habit in to a particular feeding al distinct actions, i.e.: prehension, selection (filter- ways, thicken- (e.g. vomero-palatine organ). Posteriorly, a ing), mastication, deglutition and digestion. Accord- ed dorsal most of the ante- the of each studied pharyngeal pad occupies ingly, following account

rior a narrow has been subdivided thus: pharyngeal cavity, leaving only pas-

for water and food this sage particles; "palatal organ"

1. General characters (brief covered with diagnostic description is a stratified, strongly papillose, and/or

of the studied and references to Below submucosa genus), species plicated epithelium. this, the con-

earlier work done. elastic fibres sists largely of collagen and in a matrix

2. of the considered. Ecology species of connective tissue. The thick muscularis is com-

3. Functional of the mechan- morphology feeding posed of numerous muscle strands running in all di-

isms, subdivided into: well somewhat rections as as collagen fibres, etc. A

External features sense a) (rostrum, organs, lips, similar, but smaller and thinner, triangular ventral etc.) pad overlies the anterior pharynx floor, just in front b) of the Bucco-pharyngeal cavity, comprising: pharyngeal teeth area. Investigations by sever- i. The and buc- prehensile apparatus (mouth al authors (Al-Hussaini, 1949; Dorier & Bellon, cal cavity). 1952; Maltzan, 1935; Girgis, 1952, etc.) have shown

ii. The selective apparatus branchial that fishes cells in (palate, cyprinid possess numerous mucus

arches and anterior the well well-devel- pharynx). bucco-pharyngeal mucosa, as as

c) The which masticatory apparatus (posterior pharynx). oped taste buds, are particularly numerous in The d) digestive tract. the herbivorous species. These cells are more or less

4. Conclusions and discussion (adaptations, applica- concentrated locally, for instance: the concentrations

of buds barbels well the tion of results obtained to other fields, further taste on or lips, as as on

lines of research, etc.) palate and pharyngeal pad; and the high concentra- of tions mucus glands (goblet cells) in the posterior

In order to matters and avoid where are situated to simplify unnecessary pharynx, they ideally ensure efficient lubrication of the food. The repetition, a general introductory review is given histological in-

here, broadly along these lines, relating all character- vestigations carried out in connection with this sub-

these fish found in results those obtained these istics were to possess common. ject gave corroborating by

Hence, in the individualaccounts, only those features authors.

which The arches in they differ significantly from the overall gill are 4 in number, branchiostegal

and from other will be considered. 3, the membranes more or less ex- picture species rays gill usually tensively united to the isthmus ventrally. The devel-

and functional of the GENERAL CHARACTERS opment importance gill-rakers

In all fishes of this family the mouth is toothless and varies greatly in the different species, ranging from

the the of Barilius the generally more or less strongly protractile, impor- rudimentary stumps to highly spe-

in sieve mechanism of Labeo. Pseudo- tant modifications of the posterior pharynx being cialised intricate

direct relation to the first character. branchiae, often of the enclosed type, are usually

bordered the the of the bran- The upper jaw is by premaxillaries present, lying in antero-superior part