Coexisting with a Predator: How an unexpected Mantis Shrimp-Clam relationship challenges a biological principle. When clams take the risk of living alongside a predator, sometimes their luck runs out, according to a study from the University of Michigan.
| Date | August 7, 2024 |
| Source | University of Michigan |
| Summary | A new study suggests that when clams take the risk of living alongside a predator, their luck doesn’t always hold out |
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How an Unexpected Mantis Shrimp-Clam Relationship Challenges a Biological Principle:
- A long-standing question in ecology is how so many different species can coexist in the same place at the same time. The competitive exclusion principle suggests that only one species can occupy a specific niche within a biological community at any given time.
- However, in nature, researchers often observe different species sharing the same niches, living in identical microhabitats, and consuming the same food.
- Researchers investigated one such case: a specialized community of seven marine clam species living in the burrows of a predatory mantis shrimp. Six of these species, known as yoyo clams, attach themselves to the burrow walls using a long foot that allows them to spring away from danger like a yoyo. The seventh species, closely related to the yoyo clams, occupies a different niche by attaching directly to the mantis shrimp’s body and not exhibiting yoyo behavior. The researchers were curious about how this unusual clam community manages to survive.
- Researchers’re looking at a fascinating situation where all these clam species not only share the same host but have also evolved, or speciated, on that host.
- When they conducted field studies of these clams in mantis shrimp burrows, her findings defied theoretical expectations: burrows containing multiple clam species were exclusively composed of yoyo clams. In a lab experiment, when the host-attached clam species was introduced, the mantis shrimp killed all the burrow-wall clams.
- This contradicts theoretical predictions, the researchers say. According to the competitive exclusion principle, species evolving to live in different niches should coexist more frequently than those sharing the same niche. However, data, published in the journal PeerJ, indicate that the evolution of a new, host-attached niche has led to ecological exclusion, not coexistence, among these clams.
- They encountered two surprising results. One was that the species expected to coexist with yoyo clams didn’t. The second was that the host mantis shrimp could turn deadly. The interesting twist is that the only survivor was the clam attached to the mantis shrimp’s body. It killed everything else on the burrow wall and even went outside the burrow to kill one that had wandered off.
- The Mantis Shrimp-Clam relationship challenges a biological principle, competitive exclusion principle suggests that the six yoyo clam species (which share the burrow-wall niche) should occupy host burrows less frequently with each other than with the niche-differentiated, host-attached clam species. Researchers tested this by field-censusing populations in the Indian River Lagoon, Florida, capturing host mantis shrimp and sampling their burrows using a bait pump. They then created artificial burrows in the lab to observe commensal clam behavior with and without a mantis shrimp host. Just two and a half days later, nearly all the clams in the mantis shrimp’s burrow were dead.
- In Mantis Shrimp-Clam relationship challenges a biological principle, these clams are commensal organisms, they naturally live with mantis shrimp in the wild, so we had no way of knowing if this behavior occurred in nature or not. It was completely surprising.
- The exact mechanism causing the exclusion of burrow-wall and host-attached clams remains unclear. One possibility is that, during the larval stage, burrow wall clams recruit to different host burrows than host-attached clams. Another possibility is differential survival in burrows containing both types of clams, potentially triggering a lethal reaction from the host mantis shrimp.
- The researchers plan to investigate further. It could have been an artifact of the lab setup, or it might indicate that, under certain conditions, the commensal relationship between the yoyo clams and the predatory host can catastrophically break down.
- The researchers have proposed two follow-up studies on the Mantis Shrimp-Clam relationship challenges a biological principle: one to determine if both types of commensal clams can recruit as larvae to the same host burrows, and another to test whether the mantis shrimp’s predatory behavior changes when the host-attached clam species is introduced to its burrow.
FAQ on Mantis Shrimp-Clam Relationship Challenges a Biological Principle:
1. What is a mantis shrimp?
A mantis shrimp is a marine crustacean belonging to the order Stomatopoda. Despite their name, they are not actually shrimp but are related to crabs, lobsters, and other crustaceans. Mantis shrimp are known for their vibrant colors and incredibly powerful claws, which they use to hunt prey.
2. Where do mantis shrimp live?
Mantis shrimp are typically found in tropical and subtropical ocean waters, particularly in the Indian and Pacific Oceans. They live in burrows or crevices in coral reefs, rocky shorelines, and sandy sea beds.
3. What is a clam?
A clam is a type of bivalve mollusk that lives in freshwater and marine environments. It has a soft body enclosed within a hard, two-part shell. Clams belong to the class Bivalvia, which also includes mussels, oysters, and scallops.
4. Where do clams live?
Clams are found in various aquatic environments, including oceans, rivers, lakes, and estuaries. Marine clams typically live buried in sand or mud on the ocean floor, while freshwater clams can be found in rivers and lakes.
5. What is competitive exclusion principle?
The competitive exclusion principle is an ecological concept that states that two species competing for the same limited resources cannot coexist at constant population levels if other ecological factors remain constant.
In other words, if two species occupy the same niche and compete for identical resources, one species will eventually outcompete the other, leading to the exclusion of the less competitive species.
This principle is also known as Gause’s Law, named after the Russian ecologist G.F. Gause, who formulated it based on his experiments with microorganisms.
6. What is the importance of competitive exclusion principle?
The competitive exclusion principle highlights the importance of niche differentiation in maintaining biodiversity within ecosystems. Species can coexist if they use different resources or occupy different niches, thus reducing direct competition.
7. What are yo-yo clams?
“Yo-yo clams” is a term used to describe clams that exhibit a unique form of locomotion by rapidly snapping their shells together, allowing them to “jump” or move in a way that resembles the up-and-down motion of a yo-yo.