''Goniocidaris umbraculum'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of cidaroid

sea urchin Sea urchins or urchins () are echinoderms in the class (biology), class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal zone to deep seas of . They typically have a globular body cove ...

that inhabits the

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an islan ...

off the southern coasts of

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

. It is plentiful on a seabed composed of

seashell A seashell or sea shell, also known simply as a shell, is a hard, protective outer layer usually created by an animal or organism that lives in the sea. Most seashells are made by Mollusca, mollusks, such as snails, clams, and oysters ...

and

bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic animal, aquatic invertebrate animals, nearly all living in sedentary Colony (biology), colonies. Typically about long, they have a spe ...

n rubble at a depth of off

Otago Otago (, ; ) is a regions of New Zealand, region of New Zealand located in the southern half of the South Island and administered by the Otago Regional Council. It has an area of approximately , making it the country's second largest local go ...

Description

''Goniocidaris umbraculum'' grows to a

test Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film) ...

diameter of . The main spines are thick, blunt, and usually shorter that the test diameter. The ones on the

aboral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Thi ...

(upper) surface have small flat discs at the tip, and thornlike projections near the base. The test is greenish-brown and the spines are pale brown, often tinged green near the base. They are often overgrown by

epiphyte An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...

s such as

hydroids Hydroids are a life stage for most animals of the class Hydrozoa, small predators related to jellyfish. Some hydroids such as the freshwater '' Hydra'' are solitary, with the polyp attached directly to the substrate. When these produce buds, ...

sponge Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...

s and

Distribution and habitat

''Goniocidaris umbraculum'' is native to the sea around southern New Zealand; it is common in the

Foveaux Strait Foveaux Strait ( ; ) is a strait that separates Stewart Island from the South Island of New Zealand. The width of the strait ranges from about , and the depth varies between . The strait was first charted by an American Seal hunting, sealer, O ...

, on the eastern coast of South Island as far north as

Cook Strait Cook Strait () is a strait that separates the North Island, North and South Islands of New Zealand. The strait connects the Tasman Sea on the northwest with the South Pacific Ocean on the southeast. It is wide at its narrowest point,McLintock, ...

and on the

Chatham Rise The Chatham Rise is an area of ocean floor to the east of New Zealand, forming part of the Zealandia continent. It stretches for some from near the South Island in the west, to the Chatham Islands in the east. It is New Zealand's most productiv ...

, at depths between about , on coarse sand or rubble.

Ecology

This sea urchin broods its eggs, carrying them on the flared

peristome Peristome (from the Greek language, Greek ''peri'', meaning 'around' or 'about', and ''stoma'', 'mouth') is an anatomical feature that surrounds an opening to an organ or structure. Some plants, fungi, and shelled gastropods have peristomes. In mo ...

that surrounds its mouth. Prior to research into its breeding biology, only two other sea urchins that brood their young had been studied, '' Cassidulus caribaearum'' and '' Abatus cordatus'', though several arctic and subarctic species were known to do so. ''Goniocidaris umbraculum'' is a

gonochoric In biology, gonochorism is a sexual system where there are two sexes and each individual organism is either male or female. The term gonochorism is usually applied in animal species, the vast majority of which are gonochoric. Gonochorism contrast ...

species, individuals being either male or female. Spawning takes place around July. The eggs have large yolks and are buoyant, and if detached from the female, float to the surface. As they emerge from the

gonopore A gonopore, sometimes called a gonadopore, is a genital pore in many invertebrates. Hexapods, including insects, have a single common gonopore, except mayflies, which have a pair of gonopores. More specifically, in the unmodified female, it is ...

on the aboral surface of the female, the eggs are retained. They are then moved to the peristome, a process that takes several minutes and is achieved by the action of the

tube feet Tube or tubes may refer to: * Tube (2003 film), ''Tube'' (2003 film), a 2003 Korean film * "Tubes" (Peter Dale), performer on the Soccer AM#Tubes, Soccer AM television show * Tube (band), a Japanese rock band * Tube & Berger, the alias of dance/e ...

and

cilia The cilium (: cilia; ; in Medieval Latin and in anatomy, ''cilium'') is a short hair-like membrane protrusion from many types of eukaryotic cell. (Cilia are absent in bacteria and archaea.) The cilium has the shape of a slender threadlike proj ...

, the eggs being guided along channels between the spines; the peristome becomes slightly depressed in order to accommodate the eggs, which are retained by the spines surrounding the mouth for about two months. Sixty eggs can be held in place, and when the juveniles have developed tube feet, they move to other parts of the test, but continue to be brooded for another two months. This unusual reproductive strategy may have developed when this species evolved to live in the colder waters further south than other members of its genus. ''Goniocidaris umbraculum'' feeds on the bryozoan '' Filicea elegans''.

References

{{Taxonbar, from=Q2011829 Cidaridae Echinoderms of the Pacific Ocean Marine fauna of New Zealand Endemic fauna of New Zealand Animals described in 1878 Taxa named by Frederick Hutton (scientist) Endemic echinoderms of New Zealand