Dynamic Simulations Reveal Feeding and Respiration Patterns of Early Cambrian Periderm-Bearing Cnidarian Polyps

Belangrijkste concepten

The dynamic simulations show that the rate of water inhalation by the polyp subumbrella is positively correlated with the rate of contraction and expansion of the coronal muscles, which likely represents the ancestral feeding and respiration patterns of Cambrian sedentary medusozoans.

Samenvatting

The study simulates the contraction and expansion of the microscopic periderm-bearing olivooid Quadrapyrgites using computational fluid dynamics (CFD) to investigate its feeding and respiratory activities. The simulations demonstrate that a faster expansion rate leads to greater water exchange and flow velocity near the subumbrella aperture, which can improve the efficiency of food intake and gas exchange.
The formation of ring-shaped main and secondary vortices during the expansion and contraction of the polyp shares similarities with the vortex patterns observed in modern swimming medusae, suggesting that the dynamic process of sedentary Quadrapyrgites may be related to the passive energy recapture mechanism. However, constrained by the periderm structure, Quadrapyrgites likely had limited dynamic efficiency compared to modern free-swimming medusae.
The study also suggests that the increase in body size and stronger capacity of muscle contraction may have been indispensable for the stepwise evolution of active feeding and subsequent swimming in a higher flow environment, as the low Reynolds number swimming strategy can lead to lower propulsion efficiency for millimeter-scale organisms.

Statistieken

The maximum flow velocity near the peridermal aperture ranged from 0.005 to 0.0155 m/s depending on the rate of contraction and expansion.
The dynamic Reynolds number of the simulated polyp was approximately 0.96.

Citaten

"The simulations show that the rate of water inhalation by the polyp subumbrella is positively correlated with the rate of contraction and expansion of the coronal muscles, consistent with the previous feeding and respiration hypothesis."
"The dynamic simulations also show that the frequent inhalation/exhalation of water through the periderm polyp expansion/contraction conducted by the muscular system of Quadrapyrgites most likely represents the ancestral feeding and respiration patterns of Cambrian sedentary medusozoans that predated the rhythmic jet-propelled swimming of the modern jellyfish."

Belangrijkste Inzichten Gedestilleerd Uit

Dynamic simulations of feeding and respiration of the early Cambrian periderm-bearing cnidarian polyps

by Zhang,Y., Wa... om www.biorxiv.org 07-30-2023

https://www.biorxiv.org/content/10.1101/2023.07.28.550931v3

Diepere vragen

How did the feeding and respiration patterns of Quadrapyrgites and other Cambrian periderm-bearing polyps evolve into the jet-propelled swimming of modern jellyfish

The feeding and respiration patterns of Quadrapyrgites and other Cambrian periderm-bearing polyps evolved into the jet-propelled swimming of modern jellyfish through a series of transitional stages. Initially, these early Cambrian sedentary medusozoans, like Quadrapyrgites, relied on active feeding mechanisms within their periderm-covered polyps. The rhythmic contraction and expansion of the coronal muscles, along with the movement of the mesoglea layer, facilitated the intake of food particles and gas exchange. This feeding and respiration pattern was crucial for their survival in the benthic environment.
As these organisms evolved, environmental pressures and opportunities likely played a significant role in driving the transition towards jet-propelled swimming. Factors such as changes in current velocity, availability of food sources, and competition with other organisms may have influenced the need for more efficient locomotion strategies. Larger body size and stronger muscle contraction became essential for navigating higher flow environments and accessing larger quantities of food.
Over time, the sedentary polyps evolved into free-swimming medusae with the ability to propel themselves through the water column using jet propulsion. This transition involved adaptations such as the loss or degradation of the periderm, the development of longer tentacles for feeding, and the enhancement of muscle strength for more effective swimming. The evolution of jet-propelled swimming in modern jellyfish can be traced back to the ancestral feeding and respiration patterns of Cambrian sedentary medusozoans like Quadrapyrgites.

What were the potential environmental factors that influenced the feeding efficiency of Quadrapyrgites and other Cambrian sedentary medusozoans

The feeding efficiency of Quadrapyrgites and other Cambrian sedentary medusozoans was influenced by various environmental factors that shaped their feeding strategies. One key factor was the flow velocity of the surrounding water. These organisms inhabited environments with relatively low flow velocities, where they could actively feed by manipulating the contraction and expansion of their polyp subumbrella. The rate of water intake near the peridermal aperture was directly related to the expansion rate of the mesoglea layer, allowing them to access food particles efficiently.
The viscous boundary layer near the sea floor also played a role in protecting these organisms from excessive current velocities. The boundary layer reduced drag and provided a stable environment for feeding activities. However, fluctuations in flow caused by oscillating currents or uneven seafloor topography could impact the feeding efficiency of these sedentary medusozoans. In turbulent environments, the mixing of nutrients could enhance feeding efficiency, while excessively high current velocities could hinder their ability to capture food particles effectively.
Overall, the feeding efficiency of Quadrapyrgites and other Cambrian sedentary medusozoans was closely tied to the surrounding water conditions, including flow velocity, boundary layer dynamics, and the availability of food sources. These environmental factors influenced their feeding strategies and may have driven adaptations towards more efficient feeding mechanisms over time.

What insights can the dynamic simulation of Quadrapyrgites provide for understanding the evolution of body size and locomotion strategies in early metazoans during the Cambrian explosion

The dynamic simulation of Quadrapyrgites provides valuable insights into the evolution of body size and locomotion strategies in early metazoans during the Cambrian explosion. By simulating the contraction and expansion of the polyp subumbrella, researchers can better understand how these organisms interacted with their environment and adapted to changing conditions.
The simulations suggest that as body size and height increased in Cambrian sedentary medusozoans like Quadrapyrgites, the efficiency of feeding and gas exchange improved. Larger organisms had to develop stronger muscle contraction and more efficient feeding mechanisms to thrive in their environment. The transition from sedentary feeding to jet-propelled swimming likely involved a series of morphological and behavioral innovations, such as the development of longer tentacles and the ability to swim through higher flow environments.
Furthermore, the simulations highlight the importance of body size and muscle strength in the evolution of locomotion strategies. Larger organisms with the capacity for stronger muscle contraction were better equipped to navigate higher flow environments and access larger quantities of food. The stepwise evolution of active feeding and subsequent swimming in Cambrian sedentary medusozoans may have been driven by the need to adapt to changing environmental conditions and compete for resources in the ancient seas.