What do ammonites eat

In their infancy they would have been vulnerable to attack from other predators, including fish; however, they quickly assumed a strong protective outer shell that shielded their soft interior from damage. Ammonites moved by jet propulsion, expelling water through a funnel-like opening to propel themselves in the opposite direction. They typically lived for two years, although some species survived beyond this and grew very large as pictured above. Evidence of their short lives is estimated by looking at their living relatives - the nautilus.

These creatures exist within modern day seas and possess many characteristics similar to ammonites see picture below. Nautilus shells comprise of individual chambers, each growing in size as the creature grows.

These chambers are secreted by the creature at a rate of one every four weeks, equal to 13 each year. Using this as a guide an ammonite shell containing 26 chambers could be assumed to have housed the creature for two years. Like the nautilus, ammonites retained their original shell throughout their life. However it's worth noting that in comparison to modern day nautili which live in cold, deep water, ammonites preferred warm shallow waters and may have had a higher metabolism.

Consequently, it's possible that ammonites could reach larger sizes far quicker than modern day nautili. Ammonites were the predators of their time, feeding on most living marine creatures including molluscs, fish and even other cephalopods.

By analogy to modern cephalopods, their method of attack probably comprised of silently stalking their prey, then rapidly extending their tentacles to grasp the target. Once caught the prey would be devoured by the ammonite's powerful jaws, located at the base of the tentacles, between the eyes. Much of the ammonite's life was spent in shallow waters. The evidence to support this includes their diet, which could be found in the greatest volumes in the warm shallows.

It is also unlikely that their shells could withstand the high pressures present in deep water over meters. Most ammonite shells are coiled, and all contain a series of linked chambers.

The body of the ammonite was contained within the large final, open-ended section called the living or head chamber, from which the tentacles were extended to catch prey. The opening of the shell - called the aperture - was possibly covered by a protective shield that could shut to protect the ammonite from other predators.

As the animal grew, new chambers were added behind the head chamber. But some fortuitous fossilization provided the paleontologists with a rare view of what the ammonite may have actually be eating. One Baculites specimen — AMNH — contained the remains of several small invertebrates inside the buccal mass. Portions of several small isopods and a larval snail were preserved in the mouth area.

The small invertebrates could have been eaten by the ammonite, might have been feeding on the buccal mass of the dead ammonite, or might have been washed into the body of the ammonite during preservation.

In this case, predation is the most likely possibility. Instead, the diminutive animals were only found in the buccal mass. And the fact that the isopods were broken up threw support to the idea that the ammonite had actually eaten them. If the isopods and the snail were scavenging a cephalopod carcass, then we would expect the preservation process to keep their bodies intact.

Email Address:. Sign me up! Skip to content. The uncoiled ammonite Baculites used in the study. Image via Wikipedia. Like this: Like Loading This entry was posted in Geobiology, palaeontology, and evolution. Bookmark the permalink. Leave a Reply Cancel reply Enter your comment here Fill in your details below or click an icon to log in:.

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