Geodia barretti is a massive deep-sea sponge species found in the boreal waters of the North Atlantic Ocean, and is fairly common on the coasts of Norway and Sweden. It is a dominant species in boreal sponge grounds. Supported by morphology and molecular data, this species is classified in the family Geodiidae.
Morphology
External morphology
Massive sponge, often irregularly lobate, whitish to light yellow color. The inside is light brown. Surface is smooth. Oscules are grouped in more or less shallow depressions (= preoscules) while pores are spread over the whole body. There is a distinct cortex about 0.5 mm thick, it is made of ball-shaped spicules called sterrasters.
Spicules
Megascleres. Oxeas (1000-5000 µm). Dichotriaenes with rhabdomes up to 5000 µm long (more rarely orthotriaenes). Anatriaenes. Meso/protriaenes (rare).
Microscleres.
Microxeas (190-900 µm), sometimes slightly centrotylote. Sterrasters (50-130 µm). Oxyasters I (30-80 µm), microspined branches, only found in some specimens living > 1000 m. Oxyasters II (6-33 µm), microspined branches. Strongylasters (3-11 µm), microspined branches.
Genetics
DNA barcodes
Cytochrome oxidase subunit 1 gene (mitochondrial). Folmer fragment: 2 haplotypes with 1 base pair difference. One haplotype (EU442194) is present throughout the North Atlantic. The second haplotype (KC574389) has so far only been found in Flemish Cap populations. 28S rDNA (nuclear). C1-D2 domains. Genbank numbers HM592809, EU552080. 18S rDNA (nuclear). Genbank number KC481224
Genomics
One meta-transcriptome was obtained by pyrosequencing from a specimen collected south of Bergen (Norway) in 2007. Double-stranded cDNA was sequenced on a GF FLX sequencer (Roche Applied Sciences/454 Life Sciences, Barnford, CT). rRNA ribo-tags revealed a microsymbiont community, dominated by group SAR202 of Chloroflexota, candidate phylum "Poribacteria", and Acidobacteriota. The most abundant mRNAs coded for key metabolic enzymes of nitrification from ammonia-oxidizing Archaea as well as candidate genes involved in related processes.
The whole genome of this sponge was first published in 2023; it was sequenced on PacBio and Illumina (HiSeqX) platforms from a specimen collected in 2016 in Kosterhavet National Park, on the Swedish west coast. This nuclear genome assembly is 144 Mbp long (4,535 scaffolds) with a BUSCO completeness of 71.5%, while the mitochondrial genome is 17,996 bp long. Annotation of the nuclear genome found 31,884 protein-coding genes.
Systematics
Etymology
This sponge was named in honor of one of its discoverers, the biologist Lucas Barrett (1837-1862).
Vernacular names
This sponge is called "rutabaga sponge" in Norwegian (kålrabisvamp) and "football sponge" in Swedish (fotbollssvampdjur).
Type material
This sponge was collected by biologists Robert McAndrew and Lucas Barrett in 1855 on the South side of Vikna Island (formerly called Vigten or Vikten Island), North-Trøndelag, Norway, at a depth of 183 meters. It was later described by the British sponge taxonomist James Scott Bowerbank in 1858.
The holotype is a dry specimen stored at the Natural History Museum in London with the museum number BNHM 1877.5.21.1399. There are also slides of the holotype: BNHM 1877.5.21.1400 (one slide of surface and one spicule preparation) and BNHM 1877.5.21.1401 (slide of a section).
Phylogenetic relationships
According to morphology and molecular data, this species belongs to the family Geodiidae and to the genus Geodia. It also seems to belong to a clade of Geodia species that all have their oscules in depressions (including Geodia megastrella, Geodia hentscheli). This Geodia clade was given a PhyloCode name: Depressiogeodia.
Distribution
Biogeography
G. barretti is present throughout the boreal waters of the North Atlantic, where water temperature is usually 3-9 degrees Celsius. This species is present on the Swedish west coast and all along the Norwegian coast and Svalbard.
One single specimen was formally recorded from the Mediterranean Sea, in the ‘Canyon des Moines’ (south Corsica), at 167 m (water temperature was 13 °C). Deeper specimens (1100-1700 meter depths) were also recorded off the Atlantic coast of Morocco (Ibero-Moroccan Gulf). Several deep specimens were collected on the mid-Atlantic ridge at 1650 m depth.