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Figure 1. Dinophysis caudata, living cell.


Figure 2. D. caudata, scanning electron microscope (SEM) image.


Figure 3. D. caudata v. acutiformis, living cell.

Species Name: Dinophysis caudata Saville-Kent 1881
Common Name: Dinoflagellate
Synonymy: Dinophysis diegensis Kofoid 1907
Dinophysis homunculus Stein 1883
Dinophysis tripos Gourret 1883
  1. TAXONOMY

    Kingdom Phylum/Division Class: Order: Family: Genus:
    Protista Dinophyta Dinophyceae Dinophysiales - Dinophysis

    Use your mouse to rollover the terms in purple for their definitions. If this feature is not supported by your browser, please refer to the accompanying glossary for terminology.

    Species Description

    Dinophysis caudata is a unicellular thecate dinoflagellate with a laterally compressed cell, a large hypotheca and a comparatively small epitheca. Species of Dinophysis normally have 19 plates. The majority of the cell size consists of the four plates of the hypotheca, and there are also six in the epitheca, four in the cingulum and five in the sulcus. Except for the hypotheca, most plates are not visible. In D. caudata, the cingulum and sulcus have transparent extensions on either side called lists (see general morphology illustration of Dinophysiales on the Dinoflagellates page), smaller on the cingulum and well developed on the sulcus. Sulcal lists have ribs, normally three, and the left sulcal list is larger than the other. Within the genus, these features have identification significance. The anterior cingular list is funnel-shaped and conceals the epitheca in the broad lateral view of the cell.

    The widest part of the cell is below the median, usually at the level of the third sulcal list. The dorsal side of the cell is slightly convex, and the ventral side is straight. Overall morphology is apparently highly variable. At least 12 different varieties and forms have been described, of varying levels of validity and taxonomic distinction. Some forms bear a close resemblance to D. siankanensis (Becerril & Hernandez-Becrril 2002). The type variety is characterized by a comparatively long finger-like posterior extension (Figures 1, 2) that terminates in a pointed tip (Figures 2, 5). This variety is not common in the IRL. More frequent locally is the variety acutiformis, which either lacks the posterior extension or has one that is much reduced (Figures 3, 4). Intermediate forms are also present in the IRL (Figure 5). The surface of the cell is uniformly rugose or granular. Recently divided cells (mirror images joined dorsally at the widest part of the hypotheca, Figure 6) are fairly frequent, suggesting that daughter cells do not separate immediately after division.

  2. HABITAT AND DISTRIBUTION

    Habitat & Regional Occurence

    This species is found throughout the world in tropical and subtropical environments, mostly in estuaries and coastal waters, rarely in oceanic areas. When it is found outside of warmer waters, for example coastal Norway (Throndsen et al. 2007), it is probably the result of current transport.

    Indian River Lagoon Distribution

    D. caudata it is found in the IRL from spring to fall, and rarely seen in the Mosquito Lagoon during winter months. However, cells are never abundant.

    Size

    Literature records give a range in length of 70-170 µm and a width of 37-50 µm.

    Figure 4. D. caudata v. acutiformis. SEM image. Figure 5. D. caudata, intermediate variety. SEM image.

    Figure 6. D. caudata cell division.
  3. LIFE HISTORY AND POPULATION BIOLOGY

    Reproduction

    Reguera and coworkers (2007) have shown that the morphologically different D. diegensis is a phase of the dimorphic sexual life cycle of D. caudata. Moreover, other previously described morphologies of the species may also be life cycle stages, thus partially explaining the well noted morphological variability. Though there has been no comprehensive genetic analysis of D. caudata from widely geographically separated strains, it appears that at least D. tripos is closely related genetically (Gómez et al. 2011), and is sometimes considered to be synonymous with D. caudata.

    Trophic Mode

    Dinophysis caudata is one of several species in the genus that are mixotrophic (both predatory and photosynthetic), with a number of chloroplasts that are orange-red to yellow-green (Figures 1, 3, 6). There is evidence that these are kleptochloroplasts, physiologically functional plastids captured from prey (Park et al. 2010; Minnhagen et al. 2011), which have been actively ingested through a peduncle feeding tube (Nishitani et al. 2008).

    Toxicity

    Toxicity has long been known in D. caudata, at least in other parts of the world. Some strains produce dinophysistoxin, PTX-2 (Pectenotoxin), or okadaic acid - all of which have potential for diarrhetic shellfish poisoning (DSP) in humans (Hallegraeff et al. 2003 ) and often result in massive fish kills. However, no illness has been attributed to DSP in the IRL system. To what extent toxin production is related to genetic differences or environmental variability is not known.

  4. PHYSICAL TOLERANCES

    No information is available at this time

  5. COMMUNITY ECOLOGY

    No information is available at this time

  6. ADDITIONAL INFORMATION

    No information is available at this time

  7. REFERENCES

    Becerril, AA & DU Hernández-Becerril. 2002. Dinophysis siankanensis, a new species of planktonic dinoflagellate (Dinophyceae) from the Mexican Caribbean Sea. Phycologia 41: 374-381.

    Fernández, L, Reguera, M, González-Gil, S & A Miguez. 2006. Pectenotoxin-2 in single cell isolates of Dinophysis caudata and Dinophysis acuta from the Galician Rias (NW Spain). Toxicon 48: 477-490.

    Gómez, F, López-García, P & D Moreira. 2011. Molecular phylogeny of dinophsoid dinoflagelates: the systematic position of Oxyphysis oxytoxoides and the Dinophysis hastate group (Dinophysiales, Dinophyceae). J. Phycol. 47: 393-406.

    Hallegraeff, GM, Anderson, DM & AD Cembella (Eds.). 2003. Manual on Harmful Marine Microalgae. Monographs on Oceanographic Methodology 11. UNESCO Publishing, Paris. 793 pp.

    Minnhagen,  S, Kim, M, Salomon, PS, Yih, W, Granéli, E & MG Park. 2011. Active uptake of kleptoplastids by Dinophysis caudata from its ciliate prey Myrionecta rubra. Aquat. Microb. Ecol. 62: 99-108.

    Nishitani, G, Nagai, S, Sakiyama, S & T Kamiyama. 2010. Successful cultivation of the toxic dinoflagellate Dinophysis caudata (Dinophyceae). Plank. Benthos Res. 3: 78-85.

    Park, MG, Kim, M, Kim, S & W Yih. 2010. Does Dinophysis caudata (Dinophyceae) have permanent plastids? J. Phycol. 46: 236-242.

    Reguera, B, González-Gil, S & M Delgado. 2007. Dinophysis diegensis is a life history stage of Dinophysis caudata (Dinophyceae, Dinophysiales). J. Phycol. 43: 1083-1093.

    Throndsen, J, Hasle, GR & K Tangen. 2007. Phytoplankton of Norwegian Coastal Waters. Almater Forlag AS, Oslo. 343 pp.

Unless otherwise noted, all images and text by PE Hargraves
Editing and page maintenance by LH Sweat
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Page last updated: 14 June 2011

PEDUNCLE

Cytoplasmic appendage near the flagellar pores. This organelle is associated with phagotrophy.

SEXUAL REPRODUCTION

Process of reproduction in dinoflagellates that involves the production of gametes that are fused to create a zygote.

RIBS

Supports for sulcal lists.

LISTS

Membranous extensions of the cingulum and/or sulcus that extend beyond the cell wall boundary. Found in thecate dinoflagellates, especially those from the order Dinophysiales.
SULCUS

A longitudinal furrow, often partially enclosing the propulsive flagellum.
CINGULUM

A furrow encircling the cell that contains the rotatary flagellum.

EPITHECA

The part of a dinoflagellate cell above the cingulum. Usually refers to a thecate (with cellulose plates) cell. May also be known as the epicone or episome.
HYPOTHECA

The part of a dinoflagellate cell below the cingulum. Usually refers to a thecate (with cellulose plates) cell. May also be referred to as the hypocone or hyposome.
THECATE / THECAL

Dinoflagellates possesing a cell wall comprised of cellulose plates, which have special designations and symbols according to their location on the cell. See glossary for more information.

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