Nanomia bijuga

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Nanomia bijuga
Image from page 232 of "Introduction to zoology; a guide to the study of animals, for the use of secondary schools;" (1900) (14598340930).jpg
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Domain: Eukaryota
Kingdom: Animalia
Phylum: Cnidaria
Class: Hydrozoa
Order: Siphonophorae
Family: Agalmatidae
Genus: Nanomia
Species:
N. bijuga
Binomial name
Nanomia bijuga

Nanomia bijuga, first described by Stefano Delle Chiaje in 1844 and originally named Physsophora bijuga, is a species of mesopelagic siphonophore in the family Agalmatidae [1] As with all members of the siphonophorae order, it is a colonial organism composed of individual zooids. [2] N. bijuga has a fairly broad distribution, and has been observed in the coastal waters off of North America and Europe. [3] The species has been found to occupy both epipelagic and mesopelagic depths. [4] They utilize specialized swimming zooids for both propulsion and escape behaviors. [5] Similar to other siphonophores, Nanomia bijuga employ stinging tentacles for hunting and defense. [2] They primarily feed on small crustaceans, especially krill. [6] [7]

Contents

Anatomy and morphology

Nanomia bijuga, like other siphonophores, is made up of genetically identical, but highly specialized, zooids. [8] The organism is comprised of two main body segments: the nectosome on the anterior end and the siphosome as the posterior. The nectosome contains a gas-filled pneumatophore at its end as well as nectophores, bell-shaped structures that assist in locomotion. The siphosome contains zooids specialized for feeding, digestion, reproduction, and protection. These zooids are organized in repeating sequences called cormidia. [9] Each cormidium contains one feeding zooid, the gastrozooid, with multiples of the other zooid types. Gonophores and gonodendrons, the male and female reproductive zooids respectively, occur together in pairs. [8]

Each gastrozooid has its own tentillum, which is used to capture and subdue prey. These tentilla house nematocysts, stinging cells that deliver toxins into the prey organism. [10] There are four different types of nematocysts found within the tentilla. Heteronemes, the largest of the nematocysts, possess a wider stinging apparatus than the other types and are primarily found at the proximal end of the tentilla. [10] Haplonemes, the most abundant type, are smaller than heteronemes and structured similarly with open tips for stinging but no distinct spiny shaft. [10] The final two types are desmonemes and rhopalonemes which are both used for adhesion to prey in order to prevent it from escaping as the stinging cells perform their function. [10]

A matured pneumatophore of N. bijuga contains five different tissues, two layers of ectoderm, two layers of endoderm, and a layer of ectodermal cells that are not connected to any basement membrane. One set of ectoderm/endoderm layers exists on the outside of the pneumatophore while the other set exists inside the external layer and acts as the gas chamber. [11]  

Distribution and habitat

Nanomia bijuga is widely distributed across all major oceans of the world except the Antarctic Ocean. [12] A few of its sighted locations are the Monterey Bay, [3] [4] the Gulf of Mexico, [13] the Sagami Bay of Japan [14] the Hansa Bay of Papua New Guinea, [15] and the Bantry Bay of Ireland. [16]

Nanomia bijuga is an epi/meso-pelagic species that can vertically migrate up to 1000 in depth, though it predominantly thrives at depths of 200-400m. [4] Their ability for long range vertical migration makes them key contributors to the deep scattering layer. [17]

Their abundance is significantly correlated with seasonality and primary production. [4] Notably, sightings coincide at spring phytoplankton blooms in the Sagami Bay. [14] Similarly, collection rates of Nanomia bijuga in the Bantry Bay of Ireland heightened in the months of May-September, with peak density in May/June, which correlated with the annual phytoplankton blooms in the region. [16]

Behavior

Nanomia bijuga employs several strategies to evade predators such as medusas, which typically move linearly. This includes sweeping areas, changing direction, and pulsing rapidly. [18] This rapid escape is facilitated by their use of nectophore thrust, [12] which are specialized swimming subunits aiding in propulsion. [5] At certain depths, Nanomia bijuga can change their body shape by retracting their tentacles when disturbed which can also assist in their rapid escape from predators. Another predator escape behavior that Nanomia bijuga use is diel vertical migration (DVM). It is thought that the shallow water and the amount of light may drive this pattern and is a method used to avoid predation. [18]

In addition to their escape techniques, Nanomia bijuga exhibit hunting behaviors similar to their escape mechanisms. They are filter feeders that extend their tentacles and when they contact prey, the siphonophore begins its rapid movement and contracts its tentacles with nematocysts, specialized stinging cells, to capture small organisms, like plankton, and bring them to their body. [19] Unlike other siphonophores, Nanomia bijuga uses rapid swimming to extend their tentacles. [7] Furthermore, they frequently relocate every few minutes to seek out new prey. [19]

Diet

Some information is still unknown about how deep sea siphonophores consume food, but at this time, it is believed that these creatures can be broken down into 3 dietary groups. In a study led by Purcell, [7] it was discovered that distinct diets could be associated with 3 unique suborders of siphonophore: the Cystonectae, Physonectae, and Calycophorae.

In comparison to the other suborders, organisms in the Physonectae have been shown to consume a larger volume of copepods than fish, ranging anywhere from 14% to 91% of their total diet. [7] Nanomia bijuga, or the common siphonophore, is a member of the Phsyonectae suborder. Despite its small size these creatures can play a substantial ecological role in deep-sea food systems. According to MBARI, when there are robust populations of  Nanomia bijuga concentrated in one area, they can collectively eat more krill than several adult whales. [6] Aside from copepods, shrimps have also been documented to make up a large proportion of this siphonophore's diet, as well as decapod larvae and chaetognaths. [7]

Taxonomy

Nanomia bijuga, a species of siphonophore, was first scientifically documented by the French zoologist Félix Dujardin in 1843. [2] Its initial description marked a significant milestone in the understanding of these colonial marine organisms, shedding light on their complex biology and ecological roles within oceanic ecosystems. [20]

Nanomia bijuga exhibits a distinctive morphology characterized by its elongated, slender colony structure. Comprising a succession of specialized zooids organized in a linear fashion, each component fulfills a specific function essential for the colony's survival. [2] These functions encompass prey capture, propulsion, and reproduction, all orchestrated within a translucent or transparent body, aiding in camouflage amidst its oceanic habitat. [2]

Over time, advancements in genetic analyses, morphological studies, and classification methodologies have prompted revisions in the taxonomy and nomenclature of siphonophores, including Nanomia bijuga. [21] These revisions reflect evolving understandings of their evolutionary relationships, genetic diversity, and ecological adaptations. Consequently, updates in nomenclature serve to refine our comprehension of the intricate relationships between species and their broader taxonomic contexts. [20]

Within the genus Nanomia, Nanomia bijuga maintains close kinship with its counterparts, such as Nanomia cara and Nanomia gracilis. These congeners share similarities in colonial structure and ecological niches, contributing collectively to the diversity and ecological dynamics of marine environments. Through genetic analyses, comparative morphology, and ecological studies, researchers elucidate the evolutionary trajectories and ecological interactions shaping the genus Nanomia, enriching our understanding of siphonophore diversity and marine ecosystem dynamics. [20]

Conservation status

As of January 2022, there is no specific information available regarding the conservation status of Nanomia bijuga on the IUCN Red List. Siphonophores, including Nanomia bijuga, are generally not individually assessed for conservation status due to their widespread distribution and lack of direct threats from human activities [2] However, it's important to note that marine ecosystems, including those inhabited by Nanomia bijuga, face various threats such as habitat degradation, pollution, climate change, and overfishing. These threats can have indirect impacts on siphonophore populations by altering their habitats, disrupting food webs, and affecting oceanic conditions. Population changes in Nanomia bijuga would require specific scientific studies and monitoring efforts, which may be limited due to the challenges of studying and tracking marine organisms, particularly those with pelagic lifestyles like siphonophores. [22]

Conservation efforts aimed at protecting marine ecosystems, reducing pollution, mitigating climate change impacts, and implementing sustainable fishing practices indirectly benefit species like Nanomia bijuga. [23] However, targeted conservation efforts for this species are likely limited by the lack of specific data on its population status and distribution.

In summary, while Nanomia bijuga may not be individually assessed for conservation status, its well-being is intricately linked to the health of marine ecosystems. Conservation actions targeting broader marine conservation goals are essential for safeguarding the habitats and resources upon which Nanomia bijuga and other marine organisms depend.

Related Research Articles

<span class="mw-page-title-main">Cnidaria</span> Aquatic animal phylum having cnydocytes

Cnidaria is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in fresh water and marine environments, including jellyfish, hydroids, sea anemones, corals and some of the smallest marine parasites. Their distinguishing features are a decentralized nervous system distributed throughout a gelatinous body and the presence of cnidocytes or cnidoblasts, specialized cells with ejectable flagella used mainly for envenomation and capturing prey. Their bodies consist of mesoglea, a non-living, jelly-like substance, sandwiched between two layers of epithelium that are mostly one cell thick. Cnidarians are also some of the only animals that can reproduce both sexually and asexually.

<span class="mw-page-title-main">Cnidocyte</span> Explosive cell containing one giant secretory organelle (cnida)

A cnidocyte is an explosive cell containing one large secretory organelle called a cnidocyst that can deliver a sting to other organisms. The presence of this cell defines the phylum Cnidaria. Cnidae are used to capture prey and as a defense against predators. A cnidocyte fires a structure that contains a toxin within the cnidocyst; this is responsible for the stings delivered by a cnidarian. Cnidocytes are single-use cells that need to be continuously replaced.

<span class="mw-page-title-main">Portuguese man o' war</span> Marine invertebrate

The Portuguese man o' war, also known as the man-of-war or bluebottle, is a marine hydrozoan found in the Atlantic Ocean and the Indian Ocean. It is considered to be the same species as the Pacific man o' war or bluebottle, which is found mainly in the Pacific Ocean. The Portuguese man o' war is the only species in the genus Physalia, which in turn is the only genus in the family Physaliidae.

<i>Obelia</i> Genus of hydrozoans

Obelia is a genus of hydrozoans, a class of mainly marine and some freshwater animal species that have both polyp and medusa stages in their life cycle. Hydrozoa belongs to the phylum Cnidaria, which are aquatic organisms that are relatively simple in structure with a diameter around 1mm. There are currently 120 known species, with more to be discovered. These species are grouped into three broad categories: O. bidentata, O. dichotoma, and O. geniculata. O. longissima was later accepted as a legitimate species, but taxonomy regarding the entire genus is debated over.

<span class="mw-page-title-main">Siphonophorae</span> Order of colonial hydrozoans with differentiated zooids

Siphonophorae is an order within Hydrozoa, which is a class of marine organisms within the phylum Cnidaria. According to the World Register of Marine Species, the order contains 175 species described thus far.

<i>Physalia</i> Genus of hydrozoans

Physalia is a genus of the order Siphonophorae, colonies of four specialized polyps and medusoids that drift on the surface of the Atlantic, Indian and Pacific oceans. Although these organisms look like a single multicellular organism, each specimen is actually a colony of minute organisms called zooids that have to work together for survival. A gas-filled bladder resembling a blue bottle provides buoyancy, and long tentacles of venomous cnidocytes provide a means of capturing prey. A sail on the float, which may be left or right-handed, propels Physalia about the sea, often in groups. These siphonophores sometimes become stranded on beaches, where their toxic nematocysts can remain potent for weeks or months in moist conditions. Both species of this siphonophore resemble a jellyfish in appearance, with their gas-filled float and cluster of polyps beneath, which can hang up to 30 or 165 ft below the surface of the sea.

<i>Velella</i> Species of cnidarian

Velella is a monospecific genus of hydrozoa in the Porpitidae family. Its only known species is Velella velella, a cosmopolitan free-floating hydrozoan that lives on the surface of the open ocean. It is commonly known by the names sea raft, by-the-wind sailor, purple sail, little sail, or simply Velella.

<span class="mw-page-title-main">Medusozoa</span> Clade of marine invertebrates

Medusozoa is a clade in the phylum Cnidaria, and is often considered a subphylum. It includes the classes Hydrozoa, Scyphozoa, Staurozoa and Cubozoa, and possibly the parasitic Polypodiozoa. Medusozoans are distinguished by having a medusa stage in their often complex life cycle, a medusa typically being an umbrella-shaped body with stinging tentacles around the edge. With the exception of some Hydrozoa, all are called jellyfish in their free-swimming medusa phase.

<i>Praya dubia</i> Species of hydrozoan

Praya dubia, the giant siphonophore, lives in the mesopelagic zone to bathypelagic zone at 700 m (2,300 ft) to 1,000 m (3,300 ft) below sea level. It has been found off the coasts around the world, from Iceland in the North Atlantic to Chile in the South Pacific.

<span class="mw-page-title-main">Hydroidolina</span> Subclass of hydrozoans

Hydroidolina is a subclass of Hydrozoa and makes up 90% of the class. Controversy surrounds who the sister groups of Hydroidolina are, but research has shown that three orders remain consistent as direct relatives: Siphonophorae, Anthoathecata, and Leptothecata.

<i>Porpita porpita</i> Species of hydrozoan

Porpita porpita, or the blue button, is a marine organism consisting of a colony of hydroids found in the warmer, tropical and sub-tropical waters of the Pacific, Atlantic, and Indian oceans, as well as the Mediterranean Sea and eastern Arabian Sea. It was first identified by Carl Linnaeus in 1758, under the basionym Medusa porpita. In addition, it is one of the two genera under the suborder Chondrophora, which is a group of cnidarians that also includes Velella. The chondrophores are similar to the better-known siphonophores, which includes the Portuguese man o' war, or Physalia physalis. Although it is superficially similar to a jellyfish, each apparent individual is actually a colony of hydrozoan polyps. The taxonomic class, Hydrozoa, falls under the phylum Cnidaria, which includes anemones, corals, and jellyfish, which explains their similar appearances.

<span class="mw-page-title-main">Cydippida</span> Order of comb jellies with retractable branched tentacles

Cydippida is an order of comb jellies. They are distinguished from other comb jellies by their spherical or oval bodies, and the fact their tentacles are branched, and can be retracted into pouches on either side of the pharynx. The order is not monophyletic, that is, more than one common ancestor is believed to exist.

<i>Marrus orthocanna</i> Species of hydrozoan

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<i>Apolemia</i> Family of cnidarians

Apolemia is a genus of siphonophores. It is the only genus in the monotypic family Apolemiidae.

<i>Porpita prunella</i> Species of hydrozoan

Porpita prunella is a marine species of hydrozoan organisms within the family Porpitidae. It consists of colonies of zooids. Very little is known about this species, as there have been no confirmed sightings since its discovery in 1801 and naming by Haeckel in 1888. Being in the chondrophore group, it is likely that its behaviour is similar to the other species of the genera in the family. However there are also serious doubts as to its very existence as a separate species and may in fact be a synonym for Porpita porpita instead.

<i>Bathyphysa conifera</i> Species of siphonophore sometimes called the flying spaghetti monster

Bathyphysa conifera, sometimes called the flying spaghetti monster, is a bathypelagic species of siphonophore in the family Rhizophysidae. It is found in the northern Atlantic Ocean and off the coast of Southwestern Africa and California.

<span class="mw-page-title-main">Physonectae</span> Suborder of siphonophores

Physonectae is a suborder of siphonophores. In Japanese it is called 胞泳.

<span class="mw-page-title-main">Calycophorae</span> Suborder of Siphonophorae

Calycophorae is a suborder of Siphonophores alongside two other suborders Physonectae and Cystonectae. This suborder includes the giant siphonophore, ; one of the longest lengthwise extant creatures (40–50m). While the Physonectae have a pneumatophore, nectophore, and a siphosome, Cystonectae lack a nectophore, and Calycophorae lack a pneumatophore. From the bell-shaped nectophores, Physonectae and Calycophorae are called Codonophores or Greek for bell-bearers. The distribution, morphology, and behaviors of Calycophorae species are vast and greatly depend on the species. Calycophoraes typically consist of two nectophores with a siphosome that have many tentacles that grow out of the siphosome. The Calycophoraes move by propelling water out of the nectophore much like how jellyfishes move. The tentacles act as fishing nets where the nematocysts on the tentacles paralyze their prey which are then later fed on. Calycophorae have three life stages, which are the larval development stage, the polygastric stage, and the eudoxid maturation stage. Each Calycophorae colony forms from one fertilized egg.

Lensia is a genus of hydrozoans belonging to the order Siphonoporae and the family Diphyidae. This genus is colonial and consists of many different types of highly specialized zooids. The genus Lensia was first established in 1932 by Dr. Arthur Knyvett Totton, who would also describe and add another 11 species during his career. As of March 2023, the genus consists of only 26 described and accepted species and an additional seven uncertain species, according to the World Register of Marine Species.

<i>Tima nigroannulata</i> Species of hydrozoa

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References

  1. ↑ Berrill NH (1930). "On the Occurrence and Habits of the Siphonophore, Stephanomia bijuga (Delle Chiaje)". Journal of the Marine Biological Association of the United Kingdom. 16 (3): 753–755. Bibcode:1930JMBUK..16..753B. doi:10.1017/s0025315400073069. ISSN   0025-3154.
  2. 1 2 3 4 5 6 Church SH, Siebert S, Bhattacharyya P, Dunn CW (July 2015). "The histology of Nanomia bijuga (Hydrozoa: Siphonophora)". Journal of Experimental Zoology. Part B, Molecular and Developmental Evolution. 324 (5): 435–449. Bibcode:2015JEZB..324..435C. doi:10.1002/jez.b.22629. PMC   5032985 . PMID   26036693.
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  8. 1 2 Dunn CW, Wagner GP (2006-12-01). "The evolution of colony-level development in the Siphonophora (Cnidaria:Hydrozoa)". Development Genes and Evolution. 216 (12): 743–754. doi:10.1007/s00427-006-0101-8. ISSN   1432-041X. PMID   16983540.
  9. ↑ Church SH, Siebert S, Bhattacharyya P, Dunn CW (July 2015). "The histology of Nanomia bijuga (Hydrozoa: Siphonophora)". Journal of Experimental Zoology Part B: Molecular and Developmental Evolution. 324 (5): 435–449. Bibcode:2015JEZB..324..435C. doi:10.1002/jez.b.22629. ISSN   1552-5007. PMC   5032985 . PMID   26036693.
  10. 1 2 3 4 Damian-Serrano A, Haddock SH, Dunn CW (2020-04-02), Shaped to kill: The evolution of siphonophore tentilla for specialized prey capture in the open ocean, doi:10.1101/653345 , retrieved 2024-04-04
  11. ↑ Church SH, Siebert S, Bhattacharyya P, Dunn CW (July 2015). "The histology of Nanomia bijuga (Hydrozoa: Siphonophora)". Journal of Experimental Zoology Part B: Molecular and Developmental Evolution. 324 (5): 435–449. Bibcode:2015JEZB..324..435C. doi:10.1002/jez.b.22629. ISSN   1552-5007. PMC   5032985 . PMID   26036693.
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  17. ↑ Barham EG (May 1963). "Siphonophores and the Deep Scattering Layer". Science. 140 (3568): 826–828. Bibcode:1963Sci...140..826B. doi:10.1126/science.140.3568.826. PMID   17746436.
  18. 1 2 Hunt JC, Lindsay DJ (1998). "Observations on behavior of Atolla (Scyphozoa: Coronatae) and Nanomia (Hydrozoa: Physonectae): use of the hypertrophied tentacle in prey capture" (PDF). Plankton Biology & Ecology. 45 (2): 239–242.
  19. 1 2 Robison BH (2004-03-31). "Deep pelagic biology". Journal of Experimental Marine Biology and Ecology. 300 (1): 253–272. doi:10.1016/j.jembe.2004.01.012. ISSN   0022-0981.
  20. 1 2 3 "Nanomia bijuga Taxonomy ID: 168759". NCBI taxonomy database. National Center for Biotechnology Information, U.S. National Library of Medicine.
  21. ↑ Dunn CW, Wagner GP (December 2006). "The evolution of colony-level development in the Siphonophora (Cnidaria:Hydrozoa)". Development Genes and Evolution. 216 (12): 743–754. doi:10.1007/s00427-006-0101-8. PMID   16983540.
  22. ↑ "Taxonomy: Nanomia Bijuga". National Biodiversity Data Centre. 2015.
  23. ↑ "Jellyfish, Helping to Keep Our Ocean Full of Life". Marine Conservation Society. United Kingdom. 2024.
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