Kaedah Penyu Berenang

chewan

Penyu berenang dalam satu garisan lurus                  
                  
               
                LONDON - Haiwan ini memang terkenal dengan kemampuan berenang sehingga ribuan kilometer dan menyeberangi lautan berombak.

Tetapi sehingga hari ini, tidak ramai yang sedar kebolehan luar biasa penyu dalam pengemudian arah.

Penyu betina dewasa dilaporkan mampu berenang sehingga ribuan kilometer di lautan dalam satu garisan lurus, menurut kajian terbaru sepasukan saintis dari Universiti Exeter, Britain.

Haiwan itu didapati mampu melakukan perjalanan jarak jauh dari Afrika Tengah ke Amerika Selatan menggunakan laluan paling pendek dengan keupayaan semulajadinya, menewaskan teknologi kapal layar tercanggih dunia.

Kemampuan penyu untuk berenang ribuan kilometer dalam satu garisan lurus masih menjadi misteri tetapi kebanyakan saintis berpendapat haiwan itu menggunakan gabungan penglihatan - berdasarkan kedudukan bintang dan matahari - dan medan magnetik bumi bagi mengemudi arah laluan.

Kajian selama lima tahun itu  menunjukkan penyu betina melakukan perjalanan sejauh 7,560 kilometer merentasi lautan Atlantik dan  mengambil masa selama 150 hari.

KimoraHakim

for sure this research took years to be completed...

dauswq

Reply 1# chewan


Independent eye movements in the turtle.

Ariel M.

Department of Behavioral Neuroscience, University of Pittsburgh, PA.

Abstract
In order to evaluate the normal eye movements of the turtle, Pseudemys scripta elegans, the positions of each eye were recorded simultaneously using two search-coil contact lenses. Optokinetic nystagmus (OKN) was strikingly unyoked in this animal such that one eye's slow-phase velocity was substantially independent of that of the other eye. On the other hand, the fast-phase motions of both eyes occurred more or less in synchrony. An eye's slow-phase gain is primarily dependent on the direction and velocity of the stimulus to that eye. Using monocular stimuli, the highest mean gain (0.54 +/- 0.047; mean +/- standard error of mean) occurred using temporal-to-nasal movement at 2.5 deg/s. The mean OKN gain for nasal-to-temporal movement was only 0.13 +/- 0.015 at that velocity. Additionally, using the optimal monocular stimulus (temporal-to-nasal stimulation at 2.5 deg/s) only drove the occluded eye to move nasal-to-temporally at 0.085 deg/s, equivalent to a "gain" of only 0.034 +/- 0.011. The binocular OKN gain during rotational stimuli was higher than monocular gain, especially during nasal-to-temporal movement at high velocities. Also the difference in slow-phase eye velocity between the two eyes was smaller during binocular rotational stimuli. In contrast, when each eye simultaneously viewed its temporal-to-nasal stimulus at an equal velocity, two behaviors were observed. Often, OKN alternated between an animal's left eye and right eye. Occasionally, both eyes moved at equal but opposite velocities. These behavioral data provide a quantitative baseline to interpret the properties of the retinal slip information in the turtle's accessory optic system. Those properties are similar to the behavior of the turtle in that both are tuned to direction and velocity independently for each eye (Rosenberg & Ariel, 1990).

Kesimpulan: Setiap mata kiri & kanan penyu memberikan arah dan magnitud halaju yg berbeza antara satu sama lain...this vector of -y + y cancelled each other..sbb tu halaju kedua-dua akan coupled together to point into one direction, memberikn halaju pada garisan lurus


Sumber: http://www.ncbi.nlm.nih.gov/pubmed/2271458