Despite the enormous ecological and economic importance of coral reefs, the keystone organisms in their establishment, the scleractinian corals, increasingly face a range of anthropogenic challenges including ocean acidification and seawater temperature rise [1][2][3][4] . To understand better the molecular mechanisms underlying coral biology, here we decoded the approximately 420-megabase genome of Acropora digitifera using next-generation sequencing technology. This genome contains approximately 23,700 gene models. Molecular phylogenetics indicate that the coral and the sea anemone Nematostella vectensis diverged approximately 500 million years ago, considerably earlier than the time over which modern corals are represented in the fossil record ( 240 million years ago) 5

We show here that a dinoflagellate genome exhibits unique and divergent characteristics when compared to those of other eukaryotes. Our data elucidate the organization and gene inventory of dinoflagellates and lay the foundation for future studies of this remarkable group of eukaryotes.

The smallest reported bacterial genome belongs to Tremblaya princeps, a symbiont of Planococcus citri mealybugs (PCIT). Tremblaya PCIT not only has a 139 kb genome, but possesses its own bacterial endosymbiont, Moranella endobia. Genome and transcriptome sequencing, including genome sequencing from a Tremblaya lineage lacking intracellular bacteria, reveals that the extreme genomic degeneracy of Tremblaya PCIT likely resulted from acquiring Moranella as an endosymbiont. In addition, at least 22 expressed horizontally transferred genes from multiple diverse bacteria to the mealybug genome likely complement missing symbiont genes. However, none of these horizontally transferred genes are from Tremblaya, showing that genome reduction in this symbiont has not been enabled by gene transfer to the host nucleus. Our results thus indicate that the functioning of this three-way symbiosis is dependent on genes from at least six lineages of organisms and reveal a path to intimate endosymbiosis distinct from that followed by organelles.

The crown-of-thorns starfish (COTS, the Acanthaster planci species group) is a highly fecund predator of reef-building corals throughout the Indo-Pacific region 1 . COTS population outbreaks cause substantial loss of coral cover, diminishing the integrity and resilience of reef ecosystems 2-6 . Here we sequenced genomes of COTS from the Great Barrier Reef, Australia and Okinawa, Japan to identify gene products that underlie species-specific communication and could potentially be used in biocontrol strategies. We focused on water-borne chemical plumes released from aggregating COTS, which make the normally sedentary starfish become highly active. Peptide sequences detected in these plumes by mass spectrometry are encoded in the COTS genome and expressed in external tissues. The exoproteome released by aggregating COTS consists largely of signalling factors and hydrolytic enzymes, and includes an expanded and rapidly evolving set of starfish-specific ependymin-related proteins. These secreted proteins may be detected by members of a large family of olfactory-receptor-like G-protein-coupled receptors that are expressed externally, sometimes in a sex-specific manner. This study provides insights into COTS-specific communication that may guide the generation of peptide mimetics for use on reefs with COTS outbreaks.COTS are extremely fecund mass spawners 7 , which predisposes them to population outbreaks that result in a pronounced loss of live coral cover and associated biodiversity. These outbreaks have a higher impact on reef health and resilience than the combined effects of coral bleaching and disease, and increase the susceptibility of reefs to other potentially detrimental events, such as severe storms [2][3][4][5][6] (Supplementary Note 1).Although a range of local in situ control measures have been applied with some success (Supplementary Note 1), mitigation of COTS outbreaks on the necessary regional scale requires mass-deployed, species-specific strategies. In this context, genome-encoded COTSspecific attractants that underpin spawning aggregations have substantial potential as biocontrol agents. To identify attractants, we sequenced the genomes of two wild-caught individuals separated by over 5,000 km, one from the Great Barrier Reef (GBR), Australia and the other from Okinawa (OKI), Japan (Fig. 1c, d and Extended Data Fig. 1). We also sequenced transcriptomes from external organs, and proteins released into the seawater by COTS that were aggregating or were in the presence of their main predator, the giant triton Charonia tritonis (Fig. 1b).We generated separate 384 megabase (Mb) draft assemblies for the GBR and OKI genomes (Extended Data COTS genes are labelled and are marked with red lines; other asteroids, two shades of orange and yellow lines; sea urchins, dark green; hemichordates, light green; molluscs, pink; annelids, purple; cnidarians, black; and vertebrates, blue. The three clades to which COTS sequences belong are indicated by the outer circle. The asterisk denotes the fish-specific tru...

Acorn worms, also known as enteropneust (literally, ‘gut-breathing’) hemichordates, are marine invertebrates that share features with echinoderms and chordates. Together, these three phyla comprise the deuterostomes. Here we report the draft genome sequences of two acorn worms, Saccoglossus kowalevskii and Ptychodera flava. By comparing them with diverse bilaterian genomes, we identify shared traits that were probably inherited from the last common deuterostome ancestor, and then explore evolutionary trajectories leading from this ancestor to hemichordates, echinoderms and chordates. The hemichordate genomes exhibit extensive conserved synteny with amphioxus and other bilaterians, and deeply conserved non-coding sequences that are candidates for conserved gene-regulatory elements. Notably, hemichordates possess a deuterostome-specific genomic cluster of four ordered transcription factor genes, the expression of which is associated with the development of pharyngeal ‘gill’ slits, the foremost morphological innovation of early deuterostomes, and is probably central to their filter-feeding lifestyle. Comparative analysis reveals numerous deuterostome-specific gene novelties, including genes found in deuterostomes and marine microbes, but not other animals. The putative functions of these genes can be linked to physiological, metabolic and developmental specializations of the filter-feeding ancestor.