Invertebrate Biology

Invertebrates encompass more than 95 % of all animal species and occupy virtually every aquatic and terrestrial habitat on Earth, from deep-sea vents to alpine meadows. Major groups include arthropods (insects, crustaceans, spiders), molluscs (snails, bivalves, cephalopods), annelids (worms, leeches), cnidarians (corals, jellyfish) and echinoderms (sea urchins, starfish). They display astonishing morphological and ecological diversity: some are sessile filter feeders, others are active predators, herbivores, detritivores or parasites; life cycles range from direct development to complex metamorphoses. Invertebrates play pivotal roles in nutrient cycling, pollination, reef building and soil structure, and provide materials such as silk, shellac and pearl. They have inspired biomimetic materials and microfluidic devices, and underpin global fisheries and aquaculture. Contemporary challenges include documenting rapid losses in insect biomass, understanding resilience to climate change and designing ethically informed practices in farming, harvesting and research. Integrating genomics, high-resolution imaging and biomechanics is rapidly advancing our mechanistic understanding of invertebrate structure, function and adaptation.

Research from Nature Portfolio

Analyses of shell-dwelling crustaceans have compared three methods—water filling, sand filling and computed tomography—to measure internal shell volume. While water and sand give comparable estimates for small, simple shells, precision falls for larger or architecturally complex specimens. Computed tomography yields more reproducible—but consistently lower—volume measures, revealing air pockets in filled shells and suggesting methodological refinements for ecological studies of shell-occupying invertebrates.

Laboratory assays of sea urchins exposed to graded hyposalinity (32 ‰ to 14 ‰) showed that coordination of tube feet activities—measured by righting and locomotion—declines at moderate salinity reductions, whereas adhesive strength per unit area remains robust until more severe stress. These results indicate that attachment mechanics and neuromuscular control are differentially sensitive to salinity, with implications for survival during freshwater influxes.

Three G-protein-coupled receptors for the neuropeptide elevenin were cloned from the mollusc Aplysia californica and shown to require an intact disulfide bond for activation. Using inositol monophosphate assays, the study demonstrated low nanomolar peptide potency and identified conserved amino-acid residues essential for receptor sensitivity. These findings establish the molecular basis of elevenin signalling in molluscan neural circuits.

Research from all publishers

Field surveys of two co-occurring terrestrial hermit crab species demonstrated that they coexist by selecting distinct shell morphologies: one species favours short, globose shells that maximise reproductive space, while the other prefers elongated forms that enhance defence. Morphometric analyses and preference experiments confirmed intrinsic shape biases, providing a clear empirical example of resource partitioning in a naturally limiting habitat.

In tubular flow assays, juvenile sea urchin tube feet were exposed to steady laminar shear flows in upwelling, downwelling and horizontal orientations. Larval kinematics adjusted orientation-specifically to persistent hydrodynamic cues, enhancing depth regulation and area-restricted searching. Such behaviour suggests that even early life stages exploit steady flow features to forage efficiently and orient towards settlement substrates.

Invertebrate Biology publication trend

The graph below shows the total number of articles in invertebrate biology across all publications each year (not limited to Nature Index journals).

Technical terms

Computed tomography (CT): A non-invasive imaging technique that uses X-rays to reconstruct three-dimensional internal structures, such as shell cavities, at high resolution.

Disulfide bond: A covalent linkage between two cysteine residues in a peptide that stabilises its three-dimensional structure and is often essential for biological activity.

Disc tenacity: The adhesive strength per unit area of a sea urchin tube foot’s adhesive disc, typically measured in force per square millimetre.

G-protein-coupled receptor (GPCR): A membrane receptor that transduces extracellular signals via heterotrimeric G-proteins to regulate intracellular second-messenger pathways.

Resource partitioning: The division of limited resources among co-occurring species through differences in preference or use, reducing direct competition and enabling coexistence.

References

1. Gastropod shell size and architecture influence the applicability of methods used to estimate internal volume. Scientific Reports (2018).
2. Hyposalinity reduces coordination and adhesion of sea urchin tube feet. Journal of Experimental Biology (2023).
3. Identification of three elevenin receptors and roles of elevenin disulfide bond and residues in receptor activation in Aplysia californica. Scientific Reports (2023).
4. Shell resource partitioning as a mechanism of coexistence in two co-occurring terrestrial hermit crab species. BMC Ecology and Evolution (2020).