Image of a cydippid stage of a sea walnut comb jelly (Mnemiopsis leidyi) with its stereotypical tentacles and translucent body.

#CtenophoreFunFacts: Cydippids are a common life stage across the Ctenophora phylum. With tiny (.05-3 cm) ovoid bodies, they have retractable tentacles to capture prey. In a phenomenon known as dissogeny, cydippids can sexually mature to produce eggs & sperm. Image credit: @joanjsoto.bsky.social 🪼🥁

A sticky thicket of glue cells: A comparative morphometric analysis of colloblasts in 20 species of comb jelly (phylum Ctenophora) | Ciencias Marinas Ctenophores in the class Tentaculata are distinct from Cnidarians in that they use sticky, not stinging, tentacles to capture and subdue their prey. The structures that make these tentacles sticky are colloblasts, specialized multicellular adhesive structures for predation. Located on the tentacles, tentacle side-branches (tentilla), or oral tentilla, colloblasts are only found in comb jellies (phylum Ctenophora). To perform comparative anatomy of the diversity of ctenophore colloblasts, specimens were collected from the epi- to bathypelagic zones near the coasts of central California and the Hawaiian Islands using blue-water divers and remotely operated vehicles. Tentacle samples were immediately fixed in a 4% formalin solution at sea, and then prepared in the lab via secondary fixation in 2% OsO4 for scanning electron microscopy (SEM). Diversity of ultrastructural characteristics was observed using SEM, and the morphometrics of the collosphere, external secretion granules, and spiral filament were recorded for 20 species, within 9 families and 9 genera, including 13 undescribed species. Morphometry of colloblasts reveals that the shape of the collosphere (the organizational unit of sticky granules) falls into 3 classifications: spherical, ellipsoidal, or non-uniform. External secretion granule deposition falls into 2 categories: clustered or patterned; the cap cell membrane was either present or absent. This morphological variation is summarized graphically and will be useful to describe the functional diversity and feeding ecology of the interesting and controversial phylum Ctenophora.

You can learn more about colloblasts in this 2020 original research paper by Leonardi et al: cienciasmarinas.com.mx/index.php/cm... #CtenophoreFunFacts 2/2

Figure 1 and text from Leonardi et al (2020): Colloblast morphology and schematic of how morphometrics were recorded (inset). The colloblast is made up of 2 different cell types that merge in the latter stages of development. The collocyte is the primary cell that comprises the colloblast and contains a majority of the organelles that are key to the function of colloblasts during predation. Cap cells produce external secretion granules and form the cap cell membrane that covers the surface of the developing colloblast. Internal secretion granules are produced by the collocyte and are anchored to the spheroid body via the radii. The elongated nucleus is located beneath the spheroid body and extends downwards into the collopod. The spiral filament coils downwards from the spheroid body and is connected to the collopod by a thin plasma bridge that breaks away upon colloblast ejection. The root and root tendrils anchor the colloblast to the denser, inner-layer of the tentacle or tentillum.

While similar in appearance, comb jellies (aka #ctenophores) are not true jellyfish as they belong to a separate Phylum. Instead of stinging cells, comb jellies have sticky cells called colloblasts, which are unique to Ctenophora. Credit image to @stevehaddock.bsky.social. #CtenophoreFunFacts 🪼🥁 1/2

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Figure 2 taken from Parry et al. 2021 Holotype specimen of Ctenorhabdotus campanelliformis sp. nov. from the Drumian Marjum Formation in Utah (A and B) Counterpart and part (mirrored) of UMNH.IP.6125, photographed immersed in water under cross polarized light; dotted line in panel (A) indicates area examined for elemental analysis. (C) Energy-dispersive spectroscopy (EDS) elemental map of carbon in the counterpart. (D) Interpretative drawing of whole specimen, colors as in Figure 1 and as shown.

Much older than dinosaurs, comb jellies have been around since the Cambrian Period (~500 mya) 🤯 Fossils found in Utah suggest early species had upwards of 24 comb rows & a sensory system! Learn more about the findings ➡️ pmc.ncbi.nlm.nih.gov/articles/PMC... 🪼🥁 Follow us for more #CtenophoreFunFacts!

Happy Easter, to those that celebrate! May your baskets be as bountiful as the daily egg production of Mnemiopsis leidyi (averages of ~10,000+ per day) #CtenophoreFunFacts 🪼🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚🥚 (1/35) 😉

Have you ever seen a #ctenophore poop? 🪼💩 While it was widely accepted that comb jellies expel waste from both ends, Mnemiopsis shattered dogma with the presence of a through-gut. Intrigued? Read the original research: www.cell.com/current-biol.... Credit video to William Browne. #CtenophoreFunFacts

Ctenophora or comb jelly: Haeckelia rubra 1, 2, Hormiphora species 3, Callianira bialata 4, Tinerfe cyanea 5, and Lampea pancerina 6. Chromolithograph by Adolf Glitsch from an illustration by Ernst Haeckel from Art Forms in Nature, Kunstformen der Natur, Liepzig, Germany, 1904.

Best known for his 1904 book "Kunstformen der Natur", Prof. Dr. Ernst Haeckel blended scientific illustrations with Art Nouveau aesthetics. Here, in Ctenophorae, he depicts comb jellies in stunning detail. Taken from tafel 27 (available for download): www.loc.gov/pictures/ite... #CtenophoreFunFacts