( ( All reptiles ) ( ( ( ( are ectothermic ) , ) ( which ( means ( that ( they ( ( rely ( on ( ( an ( outside source ) ) ( of heat ) ) ) ) ( to ( ( keep ( their ( body temperatures ) ) ) ( at ( a ( suitable level ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT All) (NNS reptiles)) (VP (VBP are) (ADJP (JJ ectothermic)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ means) (SBAR (IN that) (S (NP (PRP they)) (VP (VBP rely) (PP (IN on) (NP (NP (DT an) (JJ outside) (NN source)) (PP (IN of) (NP (NN heat))))) (S (VP (TO to) (VP (VB keep) (NP (PRP$ their) (NN body) (NNS temperatures)) (PP (IN at) (NP (DT a) (JJ suitable) (NN level))))))))))))) (. .)))
All reptiles are ectothermic, which means that they rely on an outside source of heat to keep their body temperatures at a suitable level.
(ROOT (S (NP (NNS Reptiles)) (VP (VBP are) (VP (VBN described) (PP (IN by) (NP (NP (DT the) (NN term) (NN ectothermic)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ means) (SBAR (S (NP (PRP$ their) (JJ internal) (NN temperature)) (VP (VBZ depends) (PP (IN on) (NP (NP (DT the) (NN temperature)) (PP (IN of) (NP (PRP$ their) (NN environment))))))))))))))) (. .)))
Reptiles are described by the term ectothermic, which means their internal temperature depends on the temperature of their environment.