Image of Yellow Tiger Spider Crab
Yellow Tiger Spider Crab's are a very rare drop from level 10-30 monsters (according to the World Drops page). It has a movement speed increase of 40%.
Below is a picture comparing the Yellow Tiger to a Pink Grassland spider crab.
Note the different feet and horn tip-colors, the armor, the swords behind the yellow tiger's seat, and that the leather on the Pink Grassland crab is replaced with metal on the Tiger crab. Those mentioned differences are on most crabs.