Chart text to Fishes
CR in fishes.
As the chart shows modes of CR are present in all fishes. Taking body-tail undulation to stand for hind limb activity needs an explanation at this point. In alternate leg movement the ancestral body undulation is still present to various degrees, an
d so is continuously extant through the evolution of the vertebrate classes. Alternating movement in definitely visible in the pectoral fins action of the bony fishes, And it is onlt the absence of significant pelvic fins movement (if any?) that disqualifui
es us from seplaiokng of finr and hund appendage coactitivity. Indeed, in the sarcopterygian fishes pelvic fin mobility is certain in that eventually movement on land arose in
Alternate symmetrical mode can be said to appear in body-tail undulation for this reason.
Alternate asymmetry is basic to the Elasmobranch sharks which propel themselves with body-tail undulation assisted relatively immobile pectoral fins. (The cambered cross section of these fins, as in bird or airplane wings, enable them as act
as hydroplanes.) Another asymmetric behavior is found in pectoral fin
fanning practiced by sticklebacks and cichlids. (GT: it is
not certain to me whether the fin action is parallel or alternating. Also, this behavior may more porperly beling in the mixed mode category since there may very well be body-tail undulation to counter any displacement of the fish due to the pectora
l fanning. Fanning circulates water over eggs in a nest, so the parent engaged is to stay in place over the nest.)
PArallel symmetrical action is basic to pectoral fin propulsion by perhaps a majority of the evolutionaorily advanced Perciform fishes.
PArallel asymmetry is evident in rays and skates, where locomotion is generated by the enromously enlarged ppectroal fins undulating in the horizontal plane. THere may be a small measure of alternating activity in the caudal section of the b
ody, as the tails can defintiely oscillate horizontally. Since the earliest fish, in relevant ways similar to the rays and skates, were bottom feeders, some pectorla fin maneubverability ability must have exsited in order to control elevating or descending
movement with realtion to the substrate. Gliding by the so-called flying fishes is another example. The parallelism of the pectoral fins laterally extended through the glide is obvious. Another example is the
Mudskippers, family Goboidae: which terrestrially drag themselves by both alternating and parallel pectoral fin movement. (see video).
The mixed mode is actually universal to fishes as long as body-tail undulation is considered hind-limb activity becasue this behavior is continuously coactive with pectoral fin sterring and maneuvering in all bony fishes, which in turn may be moving
in parallel or in alternate. As mentioned above fanning may occur in the mixed mode, as well.
Flying fishes show a definite mixture of modes. Family Exocoetidae, Genus Cypselurus flying fish extends its pelvis fins as well, thereby showing symmetry, but asymmetry takes over as the gliding fish keeps its long tail vibrating in the water to maintain f
orward thrust.
BCP to MPP propulsion
Undulation is one of the few fundamental methods of animal locomotion in. And it is present almost universally all vertebrates.(even in Cf. sperm cell, or in different phyla: jellifishes, protozoans Euglena even bacteria). But fish e
volution had already developed and perfected another form of transport, that of drag- and lift-based propulsion, involving first fin and later limbs. It had been generally thought, in an Aristotelian fashion, that pectoral fins in fish only played a role in
steering and maneuvering. But it is often apparent through viewing visual data or fish in aquaria that certain fish move themselves with pectoral fin strokes. It was noted that "many reef fishes use pectoral swimming to achieve very fine motion control suc
h as backward motion, by keeping their bodies still and using their pectoral fins like oars. (http://www.dgp.toronto.edu/peopletu/thesis/ node61.html... O^O!!) As early as 1937 (Harris), and more recently (1979-1997) studies have clearly stated that
a propulsive mechanism is at work in the pectoral fin behavior of advanced teleost fishes. (Gibb et al.1994.)
From undulation to pectoral swimming
Evolution from the earliest purely body-tail undulatory method to an advanced pectoral fin propulsive capacity can be described as a tendency for the body region of undulation to be gradually reduced in the caudal direction, finally being confined to the ta
il, and simultaneously to assign the locomotory role to the body anterior. Studies (cite ... ) have classified fish propulsion into two groups, body and/or caudal fin generated and median and/or pectorla fin generated.
In BCP or body and caudal fin method, these agents in different relative proportions, generate thrust, while in the other this is done by the median and/or the pectoral fins.
In MPP or median/paired fin propulsion the pectoral and median fins cooperate in varying proportions.The two median fins are single fins, one being the dorsal, and the other the anal. In the propulsion of rays and skates (Rajiform
) the especially enlarged pectoral fins undulate in the horizontal plane. In the bowfin (Amniiform), electric fishes (Gymnotiform), triggerfishes (Balistiform), and Ocean Sunfish (Tetraodontiform) propulsions various combinat
ions and proportions of the dorsal and anal fins produce thrust. In the puffersfishes (Diodontiform) mode the pectoral fins perform undulation. Significantly, in the wrasses (Labriform) behavior the pectoral fins oscillate, that is go throug
h cyclic motion patterns. This applies widely to the entire order Perciformes (perches and allies). These patterns have been described as performing not only drag-based (oaring) but aslo lift-based locomotion comparable to that of insect, mammalian and avia
n flight. (Walker and Westneat, Labriform propulsion...1997)
Labriform propulsion is most advanced in the order Perciformes, that co-incindentally is the largest and most diversified order of vertebrates known with c. 9500 of a total of over 24,000 fish species, and has reached advanced specialization
s...including parenting behavior (among cichlids and sticklebacks) in raising, gurading and feeding? young in ways almost comparable to that in birds and mammals.
The role of the caudal fins in Labriform behavior has not been examined. This may be interesting since in the advanced perches and allies the caudal fins, lying on the ventral side, are actually in line or even anterior to the pectoral fins, where t
hey must necessarily in some way be closely coactive with the pectorals.