Why Did Vertebrates Leave the Sea for the Land?

Our prehistoric aquatic ancestors didn’t simply decide one day to leave the water and live on land. The evolutionary process that led crocodile-like creatures to grow legs took millions of years. By studying fossils, researchers at Northwestern University have concluded that the process actually began with an increase in the size of those ancient animals’ eyes, hypothesizing that seeing prey on land kick-started the anatomical changes. The researchers found that the eyes of aquatic vertebrates nearly tripled in size before the water-to-land transition.

What big eyes you have:

• “Why did we come up onto land 385 million years ago? We are the first to think that vision might have something to do with it,” said lead researcher Malcolm MacIver.
• Their hypothesis centers around water dwellers “seeing an unexploited cornucopia of food on land,” which “drove evolution to come up with limbs from fins,” MacIver said.
• The expanded visual range of seeing through air (instead of water) may have led to larger brains in early terrestrial vertebrates, and the ability to plan, rather than merely reacting, as fish do.

Frequently Asked Questions

What prompted vertebrates to move from aquatic to terrestrial environments?

Vertebrates likely moved onto land in search of new food sources and ecological niches with less competition and predation. Terrestrial environments offered untapped resources and a variety of habitats. This transition occurred around 385 million years ago during the late Devonian period, according to fossil records.

How did early vertebrates adapt to life on land?

Early vertebrates adapted to land through significant evolutionary changes. They developed limbs with digits for mobility on land, lungs for breathing air, and amniotic eggs that could be laid outside water. These adaptations allowed them to exploit the diverse terrestrial ecosystems and thrive in various habitats.

What were the first vertebrates to make the transition to land?

The first vertebrates to transition to land were amphibians, specifically a group known as labyrinthodonts. These early tetrapods evolved from lobe-finned fish and had both aquatic and terrestrial adaptations, which enabled them to live in both environments during the Devonian period.

Did the move to land happen all at once or gradually over time?

The move from sea to land was a gradual process that occurred over millions of years. It involved a series of evolutionary steps, each providing incremental adaptations that allowed vertebrates to better exploit terrestrial habitats. This transition was not a single event but a continuum of changes.

What role did plants play in the transition of vertebrates to land?

Plants played a crucial role in the transition of vertebrates to land by creating a hospitable environment. They provided food, oxygen, and shelter, which helped to establish sustainable ecosystems. The evolution of plants onto land preceded that of vertebrates, setting the stage for this pivotal move in evolutionary history.

Are there any modern-day vertebrates that are similar to the first land dwellers?

Modern-day amphibians, like frogs and salamanders, share similarities with the first land-dwelling vertebrates. They often have a dual life cycle that includes both aquatic and terrestrial stages, reminiscent of the early adaptations seen in their Devonian ancestors. However, they are much more specialized and adapted to current environmental conditions.