The Polynesian word tara means a sharp point ('thorn', 'spur', 'corner' etc), while tara = dollar of course is imported.

1. At first sight tara may give the impression of a fish with an enormous gap, or maybe a whale swallowing plankton and breathing up at the surface, then to turn around going down again into the deep.

Humpback whales (Wikipedia)

The surface is then a location of reversal. The normal habitat is not up in the light but down in the sea.

When in the K calendar mago (as for example in Ka4-14) and 'humpback' (*Kb2-16) both resemble the tara glyph type in having a bent 'fish tail', it is because the meaning 'turning around' probably applies to all three glyph types: