( ( Their secret ) ( ( is ( ( ( ( ( the ( rapid rate ) ) or ) reproduction ) and ) ( ( large amounts ) ( of ( eggs ( ( the female ) ( is ( able ( to produce ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP$ Their) (NN secret)) (VP (VBZ is) (NP (NP (NP (DT the) (JJ rapid) (NN rate)) (CC or) (NP (NN reproduction))) (CC and) (NP (NP (JJ large) (NNS amounts)) (PP (IN of) (NP (NP (NNS eggs)) (SBAR (S (NP (DT the) (NN female)) (VP (VBZ is) (ADJP (JJ able) (S (VP (TO to) (VP (VB produce))))))))))))) (. .)))
Their secret is the rapid rate or reproduction and large amounts of eggs the female is able to produce.
(ROOT (S (NP (DT The) (JJ female) (JJ reproductive) (NN system)) (VP (VBZ consists) (PP (IN of) (NP (NP (NNS structures)) (SBAR (WHNP (WDT that)) (S (VP (VP (VB produce) (NP (NNS eggs))) (, ,) (VP (VB secrete) (NP (JJ female) (NN sex) (NNS hormones))) (, ,) (CC and) (VP (ADVP (RB ultimately)) (VB enable) (NP (NP (NN birth)) (PP (IN of) (NP (DT a) (NN fetus))))))))))) (. .)))