Colloblasts are unique, multicellular structures found in

ctenophores Ctenophora (; : ctenophore ) is a phylum of marine invertebrates, commonly known as comb jellies, that marine habitats, inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs ...

. They are widespread in the

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s of these animals and are used to capture

prey Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not ki ...

. Colloblasts consist of a collocyte containing a coiled spiral filament, internal granules and other organelles. Like the

cnidocyte A cnidocyte (also known as a cnidoblast) is a type of cell containing a large secretory organelle called a ''cnidocyst'', that can deliver a sting to other organisms as a way to capture prey and defend against predators. A cnidocyte explosively ...

s of

cnidaria Cnidaria ( ) is a phylum under kingdom Animalia containing over 11,000 species of aquatic invertebrates found both in fresh water, freshwater and marine environments (predominantly the latter), including jellyfish, hydroid (zoology), hydroids, ...

ns, colloblasts are discharged from the animals’ tentacles, and are used to capture prey. However, unlike cnidocytes, which are venomous cells, colloblasts contain adhesives which stick to, rather than sting the prey.

Form, function, and occurrence

Colloblasts were first described in 1844. The apical surface of colloblasts consist of numerous cap cells that secrete

eosinophilic Eosinophilic (Greek suffix '' -phil'', meaning ''eosin-loving'') describes the staining of tissues, cells, or organelles after they have been washed with eosin, a dye commonly used in histological staining. Eosin is an acidic dye for stainin ...

granules that are thought to be the source of adhesion. On contact, these granules rupture, and release an adhesive substance onto the prey. The spiral filament absorbs the impact of the rupture, preventing the ensnared prey from escaping. Colloblasts are found in all ctenophores except those of the order

Beroida Beroidae is a family of ctenophores or comb jelly, comb jellies more commonly referred to as the beroids. It is the only known family within the monotypic order Beroida and the class Nuda. They are distinguished from other comb jellies by the c ...

, which lack tentacles, and the species '' Haeckelia rubra'', which use

s from cnidarian prey.

References

{{reflist, 25em, refs= {{cite journal , last=Franc , first = J.-M. , year = 1978 , title = Organization and function of ctenophore colloblasts: An ultrastructural study , journal = Biological Bulletin , volume = 155 , issue = 3 , pages = 527–541 , doi=10.2307/1540788 , jstor = 1540788 , url = https://www.biodiversitylibrary.org/part/21608 {{cite book , last1 = Harrison , first1 = Frederick W. , last2 = Kohn , first2 = Alan J. , date = 1996-12-06 , title = Microscopic Anatomy of Invertebrates, Mollusca II , isbn = 978-0-471-15447-1 {{cite book , last1=Mari-Luz , first1=Hernandez-Nicaise , year=1984 , chapter=9.7: The integument of the tentacles: the colloblast , editor1-last=Bereiter-Hahn , editor1-first=Jürgen , editor2-last=Matoltsy , editor2-first=A. Gedeon , editor3-last=Richards , editor3-first=K. Sylvia , title=Biology of the Integument Invertebrates , page=107 , publisher=Springer , location=Berlin, Heidelberg , isbn=9783642515934 {{cite journal , last1 = Leonardi , first1 = N..D. , last2 = Thuesen , first2 = E.V. , last3 = Haddock , first3 = S.H.D. , year = 2020 , title = A sticky thicket of glue cells: A comparative morphometric analysis of colloblasts in 20 species of comb jelly (Phylum Ctenophora) , journal = Ciencias Marinas , volume = 46 , issue = 4 , pages = 211–225 , doi = 10.7773/cm.v46i4.3118 , doi-access = free {{cite journal , last1 = Pang , first1 = K. , last2 = Martindale , first2 = M.Q. , year = 2008 , title = Comb jellies (ctenophora): A model for basal metazoan evolution and development , journal = Cold Spring Harbor Protocols , volume = 2008 , issue = 12 , at = pdb.emo106 , doi = 10.1101/pdb.emo106 , pmid = 21356709 Animal cells Histology