Simplify the following text for a Grade 3 native English-speaking person.
Original: Unlike the megamouth shark and whale shark , the basking shark does not appear to actively seek quarry , but it does possess large olfactory bulbs that may guide it . It relies only on the water that it pushes through its gills by swimming ; the megamouth shark and whale shark can suck or pump water through their gills .
Simplified: It is the second largest shark ( after the whale shark ) .