Echinodiscus tenuissimus

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18-Jan-2025 5:43 am IST, New Delhi

Echinodiscus tenuissimus is a species of sea urchin, classified under the family Astriclypeidae. It was first described by L. Agassiz and Desor in 1847. This species is part of the order Clypeasteroida, commonly known as sand dollars, which are a type of irregular sea urchin.

The physical structure of Echinodiscus tenuissimus includes a test, or shell, which is typically flat and disc-shaped, characteristic of sand dollars. Sea urchins, including this species, move using tube feet operated by a water vascular system, allowing them to navigate their environment efficiently.

Introduction
Taxonomy
Ecology and Habitat
Morphology
Distribution
Significance and Research
References

Introduction

Echinodiscus tenuissimus is a species of sea urchin within the class Echinoidea, a group known for its distinctive round bodies covered with spines. The species was first described by L. Agassiz and Desor in 1847. As a member of the family Astriclypeidae, it shares several characteristics with other species in the genus Echinodiscus, but it also has unique features that distinguish it within its family.

Like other sea urchins, Echinodiscus tenuissimus plays an important role in marine ecosystems, especially in benthic communities. Its relatively small size and specific environmental preferences make it an interesting subject for study in marine biology, particularly in the areas of echinoderm behavior and ecology. This article explores the taxonomy, morphology, ecology, and distribution of Echinodiscus tenuissimus, as well as its significance in the scientific community.

Taxonomy

The taxonomy of Echinodiscus tenuissimus places it within the phylum Echinodermata, which includes starfish, sea cucumbers, and other types of sea urchins. Specifically, it belongs to the class Echinoidea, which contains many species of sea urchins. These species are known for their spherical or disc-shaped bodies, covered in hard calcareous plates and spines.

The full taxonomic classification of Echinodiscus tenuissimus is as follows:

Kingdom: Animalia
Phylum: Echinodermata
Class: Echinoidea
Order: Clypeasteroida
Family: Astriclypeidae
Genus: Echinodiscus
Species: Echinodiscus tenuissimus

This species is part of the larger group of sea urchins within the order Clypeasteroida, which includes other burrowing and disc-shaped species. The family Astriclypeidae is characterized by sea urchins that typically have a flattened, circular shape, often with distinct features such as prominent spines or specialized adaptations to their environments.

Ecology and Habitat

Echinodiscus tenuissimus is found in shallow marine habitats, where it typically inhabits sandy or muddy substrates. These sea urchins are benthic organisms, meaning they live on the ocean floor, where they can burrow or stay buried in sediment for protection. The species is often associated with the intertidal zone and subtidal environments, where water movement and the availability of food sources are conducive to their survival.

The diet of Echinodiscus tenuissimus mainly consists of organic matter found within the sediment. This includes algae, detritus, and microscopic organisms that live within the sand. As filter feeders, they play an important role in nutrient cycling by contributing to the breakdown of organic material.

The habitat preferences of Echinodiscus tenuissimus allow it to avoid many predators, though it is still preyed upon by certain fish species, birds, and larger invertebrates. Its ability to burrow into the sediment provides a significant level of protection from predators, making it a successful member of its ecosystem.

Morphology

Echinodiscus tenuissimus exhibits the characteristic features of many sea urchins. Its body is disc-shaped and covered in spines, which provide both protection and mobility. These spines are not only used for defense but also help the organism move through the sediment and remain stable in shifting environments.

One of the distinguishing features of Echinodiscus tenuissimus is its relatively small size, which contrasts with some larger species of sea urchins. The test (the hard shell) of Echinodiscus tenuissimus is typically flattened and covered with a series of radiating patterns of spines, which are particularly prominent at the edges of the disc. These spines are thin and delicate compared to other more robust sea urchins.

Another key feature is its mouth, located at the center of the underside of its body, which is used to gather food from the surrounding environment. This is typical for sea urchins, which have a unique feeding structure known as Aristotle’s lantern—a set of complex jaw-like structures that allow them to scrape and ingest food particles.

Distribution

The species is primarily distributed in the shallow marine waters of the Atlantic Ocean. It has been observed in various regions along both the American and European coasts, although it is less common in more temperate waters. The species thrives in areas with stable sediment conditions and a steady supply of food, but its distribution can be affected by environmental factors such as water temperature and salinity.

The populations of Echinodiscus tenuissimus are not considered to be endangered, but their numbers can fluctuate depending on local ecological conditions. Changes in water quality, temperature, and the availability of food sources may impact their population dynamics over time. Researchers have studied these fluctuations to better understand the effects of environmental change on marine invertebrates.

Significance and Research

Echinodiscus tenuissimus has been the subject of several scientific studies, particularly in the fields of marine ecology and evolutionary biology. Researchers are interested in understanding how this species interacts with its environment, including its feeding habits and its role in sediment disruption and nutrient cycling. Its ability to burrow into the sediment also makes it a valuable subject of study for understanding how marine organisms can modify their habitats.

In addition to its ecological importance, Echinodiscus tenuissimus serves as an example of the diverse strategies employed by echinoderms for survival. The study of this species can provide insights into the evolution of sea urchins, particularly in terms of their morphological adaptations to benthic life.

References

World Echinoidea Database - Echinodiscus tenuissimus (L. Agassiz & Desor, 1847a)
Echinodiscus tenuissimus - Sealifebase

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