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Table 1 Biomineralization types and the presence of α-CA in various metazoan phyla

From: The evolution of metazoan α-carbonic anhydrases and their roles in calcium carbonate biomineralization

  Envir. CaCO3structure Predominant form of mineral Organic phase Calcifying cells/tissue α-CAs Technique Tissue localization Ref.
PORIFERA (appearance in Ediacaran)
Hexactinellida DS Spicules Silica, aragonite nd Sclerocytes nd - -  
Demospongia M, FW "Spongine", silicatein, silintaphin-1, chitin ✓ RT-PCR & EST lib. Adult whole organism, embryos [7]
Calcarea M Calcite, aragonite nd ✓ EST lib. Adult whole organism [45]
CNIDARIA (appearance in Ediacaran)
Octocorallia M Sclerites, spicules, skeleton High-Mg calcite Glycoproteins, lipids, polysaccharides… Calicoblastic cells ✓ biochemistry, RT-PCR, EST lib. Spicules, tentacules, polyps, larva, embryos [50]
Hexacorallia Hard skeleton Aragonite Glycoproteins, lipids, polysaccharides… ✓ EST lib., RT-PCR, genome Calicoblastic cells [9],[14],[51]-[53]
Hydrozoa M, FW Granules, skeleton Aragonite nd - EST lib., genome Polyps [54]
BRACHIOPODA (appearance in Cambrian)
Craniiformea M Shell Low-Mg calcite nd Mantle cells nd - -  
Linguliformea Ca3(PO4)2 nd nd - -  
Rynchonelliformea Low-Mg calcite Glycoproteins + polysaccharides… nd - -  
MOLLUSCA (appearance in Cambrian)
Solenogastra & Caudofoveata M Spicules Calcite, aragonite nd Mantle cells nd - -  
Polyplachophora nd - -  
Bivalvia M, FW Shell & granules Periostracum/OM ✓ RT-PCR, EST lib. Mantle, gills, adductor muscles, larva [2],[11],[13],[15]
Gastropoda M, FW, T ✓ RT-PCR, EST lib., genomes Mantle, nervous system, whole body [16],[21]
Cephalopoda M Internal shell Nautilin 63 ✓ - - [55],[56]
ANNELIDA (appearance in Cambrian)
Pogonophora M Tube & soft granules Calcite, aragonite Mucopoly-saccharides Epidermal glands ✓ RT-PCR Branchial plume [57]
ARTHROPODA (appearance in Cambrian)
Hexapoda A, T Exoskeleton Calcite Chitin, proteinaceous organic matrix Cuticle epidermis ✓ RT-PCR, EST lib., genomes Whole organism [54]
Pancrustacea A, M, FW, T Exoskeleton, gastrolithes, sternal plates, caecal concretions Calcite, vaterite, amorphous CaCO3 Cuticle epidermis, stomacal disc ✓ RT-PCR, EST lib. Larvae, oocytes, gills, epidotes, brain, antennal glands… [47],[58]-[60]
ECHINODERMATA (appearance in Cambrian)
Echinoidea M Test, teeth, spicules, spines High-Mg calcite OM Syncitium/ "fenestrated" mineral ✓ EST lib., genomes Pluteus ams, calcifying organic matrix [48],[61]
Crinoidea Articulated ossicules nd nd nd nd - -  
Ophiuroidea nd nd nd nd - -  
Asteroidea Spicules nd nd nd ✓ Biochemistry - [62]
Holothuridea Tiny spicules or ossicules nd nd nd nd - -  
UROCHORDATA (appearance in Cambrian)
Ascidiacea M Spicules Calcite OM Sclerocytes ✓ EST lib. nd [54]
Appendicularia nd nd nd nd ✓ Genome nd [63]
VERTEBRATA (appearance in Silurian)
Actinopterygii M, FW Otoliths Aragonite, vaterite Endolymphatic constituants Sacculus ✓ RT-PCR Retina, kidney, erythrocytes, gills… [49],[64]
Aves T Eggshell Calcite Uterine fluid Distal oviduct ✓ Genome Testis, retina… [54]
  1. For each taxon we collected several lines of information: the environment in which each taxon can be found (A: amphibious; DS: deep-sea; FW: freshwater; M: marine; T: terrestrial); the general calcium carbonate structure; the predominant form of the mineral; the general nature of the organic phase within the mineral (OM: organic matrix); the source of the calcifying tissue/cells; whether carbonic anhydrases have been specifically detected within these cells; the method of identification (EST lib.: EST library); tissues where CAs were detected; references to studies from which this information was collated. nd: not determined.
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