( ( Once ( ( the eggs ) hatch ) ) ( , ( there ( ( ( ( are hungry ) , ) ( young ( mouths ( to feed ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN Once) (S (NP (DT the) (NNS eggs)) (VP (VBP hatch)))) (, ,) (NP (EX there)) (VP (VBP are) (ADJP (JJ hungry)) (, ,) (S (NP (JJ young) (NNS mouths) (S (VP (TO to) (VP (VB feed))))))) (. .)))
Once the  eggs hatch, there are hungry, young mouths to feed.
(ROOT (S (S (NP (NP (DT Some) (NN species)) (PP (IN of) (NP (NN fish)))) (VP (VBP carry) (NP (PRP$ their) (VBN fertilized) (NNS eggs)) (PP (IN in) (NP (PRP$ their) (NN mouth))) (SBAR (IN until) (S (NP (PRP they)) (VP (VBP hatch)))))) (: ;) (S (NP (DT this)) (VP (VBZ is) (VP (VBN called) (S (ADJP (NN mouth) (JJ brooding)))))) (. .)))