Table 1.

Body system design options used

Ventilation DirectionCirculatory SystemExcretory SystemDigestive TractBody Temperature
Design choices
    Vertebrate and invertebrate contentUnidirectionalOpenFilters and reabsorbsCompleteHomeothermy
BidirectionalClosedSecretes onlyIncompletePoikilothermy
    Alternates for vertebrate only contentIn seriesCan concentrate urine
In parallelCannot concentrate urine
Complete anatomic division
Incomplete anatomic division