While phocid seals, walruses, and sea lions conserve heat by means of a heavy layer of blubber, fur seals and sea otters have a thick coat of fur to protect them against the cold.
(phocid seals, walruses, and sea lions; conserve; heat) (fur seals and sea otters; have; a thick coat of fur to protect them against the cold)
phocid seals, walruses, and sea lions fur seals and sea otters
conserve have
heat
a thick coat of fur to protect them against the cold