''Echinometra lucunter'', the rock boring urchin, 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 sea urchin in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Echinometridae The Echinometridae are a Family (biology), family of sea urchins in the class (biology), class Echinoidea. Characteristics All Echinometridae have imperforate tubercles and compound ambulacral plates.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) ...

(shell). It can grow to a diameter of about and grows larger at the extreme north and south ends of its range than it does in the centre. It has moderately short spines with wide bases and sharp tips. The colour of the test varies from black to deep brownish-red, often being more ruddy on its aboral (upper) surface than on its oral (lower) surface. The spines are usually black.

Distribution and habitat

''Echinometra lucunter'' is common throughout the Caribbean Sea and also occurs in Florida, Bermuda and the South American coast as far south as Brazil. It occurs on shallow rocky areas and on

coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in group ...

s usually at depths of or less but occasionally in deeper water down to about . It is sometimes found among

seagrass Seagrasses are the only flowering plants which grow in marine (ocean), marine environments. There are about 60 species of fully marine seagrasses which belong to four Family (biology), families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and ...

es and often under rock slabs or broken coral especially in places with high water movement. It sometimes occurs in large numbers and causes considerable damage to coral reefs through its boring activities.

Biology

''Echinometra lucunter'' uses the teeth that surround its mouth to grind away at the rock underneath it so as to make a hemispherical depression in which it takes refuge during the day. It emerges at night to graze on algae growing within a few centimetres (inches) of its home. It defends this hole against other sea urchins of its own species. The king helmet shell (''Cassis tuberosa'') feeds on it and several species of small

goby The Gobioidei are a suborder of percomorph fish. Many of these fishes are called gobies. It is by far the largest and most diverse order within the order Gobiiformes, and one of the most diverse groups of ray-finned fish in general. The subord ...

conceal themselves underneath its test.

References

{{Authority control Echinometridae Echinoderms of Brazil Echinoderms described in 1758 Taxa named by Carl Linnaeus