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98. A burrowing Heart Urchin


A Heart Urchin (sp.?) is burrowing itself in the sand.

Sea urchins, relatives of sea stars and sea cucumbers, move by using their spines on the side of its body and their tube feet underneath.

All irregular shaped urchins (infraclass “Irregularia”) like sand dollars (order Clypeasteroida), sea biscuits (order Clypeasteroida), and heart urchins (order Spatangoida) use their spines rather than tube feet.

These irregular shaped urchins use their spines in a rowing motion and move only in a forward path.

Regular shaped urchins use tube feet, these liquid-filled hollow skeletons are regulated through the interaction between a muscular cover and an internal fluid pressure. Muscles in the tube wall allow the sea urchins to bend or retract their feet, while increased hydrostatic pressure is used to elongate the feet. This allows them to climb on steep substrates like on the side of submerged rocks. These urchins also typically move in a random pattern. This path without any direction is called the “Brownian motion” and is typical for all urchins living on harder substrates such as rocks.

The irregular sea urchins how are living on sandy bottoms and loose substrates are often buried in their habitat. To feed they move through the sediments and detritus to consume tiny particles of organic material. Their spines are usually smaller, shorter, and softer, even fur-like, and offer little protection from hungry predators. Therefor these urchins prefer to remain buried and out of sight to protect themselves from predators like helmet shells who are active hunter of these spiny animals.


In post-production this footage was accelerated three times to keep to enhance the viewer's experience and achieve specific artistic or storytelling objectives.

Speeding up footage in post-production is a common technique in underwater documentary making, and video production in general for several reasons, including making the content more engaging and enhancing the storytelling. In the case of a heart urchin moving slowly on the sand, there are several potential reasons why the footage has been accelerated:


The natural movement of a heart urchin is too slow and uneventful for the intended pacing of the video. By accelerating the footage the audience's interest is maintained and it moves the story along more quickly.

Aesthetic Appeal:

Speeding up the footage creates a more visually dynamic and exciting sequence. It enhances the visual appeal and provides a sense of energy and motion that is absent in real-time footage.

Highlighting Details:

By speeding up the footage, we emphasise specific details or actions that might otherwise be missed by the audience in real time. This is useful for educational or documentary content to showcase particular behaviours or features of the heart urchin.

Dramatic Effect:

Accelerating the footage adds a sense of drama or intensity to the scene, even if the actual event was relatively slow-paced. This creates a more engaging viewing experience and heighten the emotional impact of this underwater videoclip.


We as underwater videographers sometime use time manipulation to convey a particular narrative or story arc. Speeding up the footage is an ideal storytelling tool to convey the passage of time, transitions, display of speed or changes in the environment.

Style and Creativity:

Accelerating this footage was also a creative choice. It allows for unique visual effects and it creates a distinct visual style.

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