Seafood through Time: Predation as a Driver of the Bathymetric Distribution of Crinoids – UROP Summer Symposium 2021

Seafood through Time: Predation as a Driver of the Bathymetric Distribution of Crinoids

Karter Burgdorf


Pronouns: He/Him/His

UROP Fellowship: CCSFP, Delta College
Research Mentor(s): Tomasz Baumiller, PhD
Research Mentor Institution/Department: College of Literature, Science, and the Arts, Department of Earth and Environmental Sciences and Museum of Paleontology

Presentation Date: Wednesday, August 4th
Session: Session 3 (5pm-6:20pm EDT)
Breakout Room: Room 3
Presenter: 1

Event Link


“Predation, arguably an important mechanism of natural selection, is thought to have played an especially significant role in the evolutionary history of crinoids. Crinoids are marine invertebrates with a very long evolutionary history (ca. 0.5 billion years). As obligate passive suspension feeders, crinoids use their arms to form a filter that captures particulate nutrients from seawater. Ecologically important traits thought to have evolved among some groups of crinoids due to predation include an increase in mobility from fully sessile to crawling to swimming; an ability to regenerate lost body parts; biochemical defenses that make them distasteful.

There are two distinct crinoid body plans: sea lilies possess a stalk, which serves to anchor the animal to the substrate and elevate the arms and the body into the water column; feather stars, a more derived group which first appeared ca. 200 million years ago, lack a stalk as adults and attach to the substrate by a set of prehensile appendages called cirri. In the geologic past, sea lilies were the dominant group and occupied both the shallow and the deep ocean. Today, they are less diverse and found only at great depths (>100 m), whereas feather stars are diverse, abundant and the only crinoids inhabiting shallow and deep water.

A favored hypothesis about the feather stars’ evolutionary success is that they are better than sea lilies at handling predation pressure, which has increased over geologic time. For example, they are much more mobile, able to move by crawling or swimming. Implicit to this hypothesis is that predation pressure decreases with depth, and sea lilies, unable to cope with high shallow-water predation, today can only survive in the deep-water refugium.
This study seeks to answer two questions relevant to the above hypothesis: (1) does predation on crinoids occur more often in shallow than deep water? (2) is the rate of regenerating lost arms faster in feather stars than sea lilies, giving the former another advantage in dealing with intense predation?

To answer the above questions, we will compare data on predation intensity and arm regeneration rates in sea lilies living at ~400 m to those of feather stars living in shallow water (~5-10 m). Data for sea lilies come from examining photographs and videos of the same individuals obtained during 8 submersible expeditions off Isla Roatán, Honduras between 2012 and 2017. Data for feather stars were obtained bimonthly in 2016-2017 using scuba off Negros Island, the Philippines. If predation has played a significant role in the success of feather stars, sea lilies should regenerate more slowly and experience fewer predation events than shallow-water feather stars.”

Authors: Karter Burgdorf
Research Method: Laboratory Research

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