The sea lily is a class of marine invertebrates that are attached to the seafloor by a stalk. They are of the class Crinoidea, otherwise known as a crinoid. These prickly creatures are part of the phylum Echinodermata. Some of the other marine creatures in this phylum are sea cucumbers, sea urchins, starfish, and brittle stars. They are also cousins of sea stars. The origin of sea lilies dates back around 480 million years, with their ancient ancestors existing many years ago. This means they were around before the dinosaurs. Scientists have found the early sea lilies in the form of fossils. These ancient animals are also cousins of sea stars.

Featured image credit: NOAA Photo Library, CC BY 2.0


Appearance

This echinoderm is known for its long feathery arms and tentacles that result in it having the appearance of a plant. This is why when many sea lilies and other crinoid specimens are close to each other on the bottom of the ocean, it can look like a sea forest. These beautiful animals possess a bunch of delicate arms that are used to capture particles of food floating by in the current.

The sea lily has an internal skeletal structure. This structure is made of a chain of plates. They also utilize stem-like stalks to attach themselves to a surface, whether that be the seabed, on corals, or simply a rock.

The sea lily has feather-like arms
The sea lily has feather-like arms

Credit: NOAA Photo Library, CC BY 2.0


Diet

The sea lily uses its arms to catch and filter tiny plankton and detritus that moves around them in the water. This method is called passive suspension feeding. Their feathery arms are not just for show, proving vital to the sea lily’s survival. Mucus covers the tissues on their arms which draw in any particles that float through them. The grabbers on the arms are called tube feet.

Habitat

Sea lilies are mostly found in deep waters in many oceans throughout the world. More specifically, they thrive in depths around 18,000 feet. They tend to settle on hard surfaces, such as rocks and coral reefs, as they need to anchor themselves to the sea floor using their stalk. They make up ‘forests’ on the seafloor, creating an ecosystem.

Sea lilies can attach to rocks and coral reefs
Sea lilies can attach to rocks and coral reefs

Credit: Alexander Vasenin, CC BY-SA 3.0


Reproduction

Sea lilies follow a more typical reproductive structure, as they are dioecious, meaning there are distinct sexual differences between females and males. Sea lilies will generate their respective gametes and release them into the water around them. This then allows the fertilization process to occur. Once successfully fertilized, the eggs will then hatch into larvae. These larvae are free-floating and help to spread the influence of the sea lily.

Threats

The sea lily is ane expert at recovering from predatory attacks. They are known to regenerate their main body parts. Amazingly, if their internal organs, or visceral mass, are affected, they can even restore these without dying. The most significant animal threat to the sea lily is the sea urchin.

Facts about the Sea Lily

  • Sea lilies are dioecious, meaning they have distinct sexes within the species.
  • They remain n one location by using their stalk as an anchor.
  • They are passive suspension feeders, allowing food particles to interact with them.


FAQs

Is a feather star a sea lily?

Although similar creatures, they are different in that a sea lily is anchored to a surface, such as a rock or ocean floor, with its stalk. Feather stars do not attach themselves to surfaces, allowing them to move freely.

What are the unique characteristics of echinoderms?

Echinoderms vary immensely in their appearance. However, they all possess two very distinctive elements. A water vascular system and five-sided radial symmetry.

What are the characteristics of a sea lily?

The sea lily typically has a bulbous body with a feather-like cluster of arms that make them look like a type of plant or tree. They also thrive in the deep ocean waters and frequently spend their adult lives on the sea floor. They attach themselves to a surface using their stalk.