Eucidaris tribuloides, the slate pencil urchin (named after slate pencil), is a species of cidaroidsea urchins that inhabits littoral regions of the Atlantic Ocean. As a member of the basalechinoid order Cidaroida, its morphological, developmental and molecular genetic characteristics make it a phylogenetically interesting species.[2]
Taxonomy
Eucidaris tribuloides was first described and classified by Jean Baptiste Lamarck in 1816 as Cidarites tribuloides.[3]
The modern classification stems from the echinoid treatises by Pomel in 1883[4] and by Döderlein in 1887.[5]
E. tribuloides has become an invasive species in some parts of the world including Maltese waters where it has been since 1998. This was the first record in the Mediterranean and is thought to have been brought there in ballast water.[11]
McPherson[6] described E. tribuloides as a "sluggish echinoid" that leads a nocturnal, benthic existence. During daylight hours, the slate pencil urchin uses its large primary spines to anchor itself under or atop rocks or to lodge itself in crevices. Individuals rarely stray far from their locality.[6] At night, they will feed primarily on corals and sponges, among other things.[12]
Biology
When its development is contrasted to the cidaroid sister subclass Euechinoidea, E. tribuloides becomes a very interesting organism from the standpoint of developmental and evolutionary biology. In euechinoid embryonic development, e.g. in the purple sea urchin, the micromeres comprise a set of four small cells that reside at the base of the vegetal plate. They are a "precociously invaginating lineage", meaning that they move into the blastocoel just prior to gastrulation; these four cells then eventually give rise to the larval skeleton.[13][14][15] Similarly, E. tribuloides also possesses a larval skeleton that arises from a special lineage of cells. In contrast, however, the number and size of its micromeres can vary (from one to three), and they do not precociously invaginate; rather, they ingress during gastrulation and bud off from the tip of the growing archenteron.[2][16] Although there are numerous molecular differences between the "spicule-forming cells" of E. tribuloides and the primary mesencyhme cells of euechinoids, these two cell lineages are thought to be homologous and have been contrasted in developmental evolution research.[17][18][19]
Reproduction
Reproduction in E. tribuloides seems to be sensitive to seasonal cycles, solar cycles, and the lunar cycle. In the Florida Keys, E. tribuloides was found to obtain peak gravidity in the late summer and early fall.[6] Populations in Panama, however, were found to be gravid in the spring, summer and fall, with peak gravidity occurring around the full moon.[20]
^Lamarck J (1816). Histoire naturelle des animaux sans vertèbres, présentant les caractères généraux et particuliers de ces animaux, Tome 3. p. 56.
^Pomel NA (1883). Classification methodique et genera des echinides vivants et fossiles. p. 103.
^Döderlein LHP (1887). Die japanischen Seeigel, I. Familie Cidaridae und Saleniidae. Stuttgart. p. 42.{{cite book}}: CS1 maint: location missing publisher (link)
^ abcdMcPherson, BF (1968). "Contributions to the biology of the sea urchin Eucidaris tribuloides (Lamarck)". Bulletin of Marine Science. 18: 400–443.
^Cerame-Vivas, MJ; Gray IE (1966). "The distributional pattern of benthic invertebrates of the continental shelf off North Carolina". Ecology. 47 (2): 260–270. doi:10.2307/1933773. JSTOR1933773.
^Santos CP, Coutinho AB, Hajdu E (2002). "Spongivory by Eucidaris tribuloides from Salvador, Bahia (Echinodermata: Echinoidea)". Journal of the Marine Biological Association of the United Kingdom. 82 (2): 295–297. doi:10.1017/S0025315402005477. S2CID85223892.
^Boveri, T (1901a). "Die Polarität der Oocyte, Ei und Larve von Strongylocentrotus lividus". Zoologische Jahrbücher. Abteilung für Anatomie und Ontogenie der Tiere. 14: 630.
^Boveri, T (1901b). "Über die polarität des Seeigel-Eies". Verhandlungen der Physikalisch-medizinische Gesellschaft zu Würzburg. 34: 145.
^Hörstadius, S (1935). "Über die determination im Verlaufe der Eiacse bei Seeigeln". Pubblicazioni della Stazione Zoologica di Napoli. 14: 251.
^Tennent, DH (1914). "The early influence of the spermatozoan upon the characters of echinoid larvae". Carnegie Institution of Washington Publication. 182: 129–138.
^Wray GA, McClay DR (1988). "The origin of spicule-forming cells in a "primitive" sea urchin (Eucidaris tribuloides) which appears to lack primary mesenchyme cells". Development. 103 (2): 305–315. doi:10.1242/dev.103.2.305. PMID3066611.
^Erkenbrack EM; et al. (2016). "Ancestral state reconstruction by comparative analysis of a GRN kernel operating in echinoderms". Development Genes and Evolution. 226 (1): 37–45. doi:10.1007/s00427-015-0527-y. PMID26781941. S2CID6067524.
^Lessios H (1991). "Presence and absence of monthly reproductive rhythms among eight Caribbean echinoids off the coast of Panama". Journal of Experimental Marine Biology and Ecology. 153: 27–47. doi:10.1016/S0022-0981(05)80004-8.