Diversity and systematics of sea anemones

Meg DalyAdorian Ardelean

Ha Rim Cha

Acknowledgments

• Michel Clareboudt, staff & faculty of Marine Sciences, SQU

• Daphne Fautin

• American Association for the

Advancement of Science, National

Science Foundation, KU Natural

History Museum & Biodiversity

Research Center

Sea AnemonesCnidaria: Anthozoa:

Actiniaria

Sea Anemones

• Cnidaria– 2 layered, organ-less

body, with stinging nematocysts

• Anthozoa– Polyp form only

• Actiniaria– Skeleton-less, solitary or

clonal (not colonial)

Subclass Hexacorallia

Actiniaria Ceriantharia Antipatharia

Zoanthidea Scleractinia

Actiniaria Antipatharia

Zoanthidea

Ceriantharia

ScleractiniaCorallimorpharia

Why study anemones?• Diverse in habitat,

biology, life history

• Understand evolution of colonies and skeletons among Anthozoa

• Understand evolution of tissues, organs, and polarity in animals

Overview

• Anemone diversity & systematics

• Morphology & variability of Actinodendridae

• Diversity & systematics of Corallimorpharia

• Systematics & Diversity of Actiniaria– Diversity

• Habitat• Biology• Life history

– Systematics• Identification• Morphology• Molecules

• Role of Biodiversity Studies – Evolution– Biogeography

Anemone diversity--typical habits

• Attached to rocks or coral skeletons– Intertidal to deep

sea

• In sand or mud– Intertidal to deep

sea

Exotic habits • On living

hermit crabs or gastropods

• On jellyfish or comb jellies

• On living sponges, corals & gorgonians

How does habit(at) manifest itself in morphology or biology?

• Shape

• Musculature

• Reproductive biology

• Symbionts

Shape

• Burrowing forms tend to be long, slender, smooth

• Intertidal forms are often “bumpy” with suckers that hold stones

• Deep water forms tend to be thick, stout, with wide oral discs

Musculature

• Burrowing forms have strong retractor and circular muscles, weak basilar muscles

• Intertidal forms have strong marginal sphincters

• Attached forms have weak circular and retractor muscles

Reproduction

• Attached forms in shallow subtidal and in deep sea have free swimming larvae, deep sea forms may have very large larvae

• Attached forms undergo longitudinal fission, burrowing forms undergo transverse fission

Symbionts

• Photosymbionts in attached and burrowing forms in shallow water

• Photosymbiotic forms have broad oral disc

• Crab symbionts tend to have potent nematocysts

How can we interpret and understand this

diversity? Taxonomy & systematics

What is it?Process of identification

• Find specimen

• Compare multiple specimens

• Develop sense of range of variation in color, shape & morphology

• Compare to descriptions of similar known species

Is it the same?Process of comparison

• Color, habitus, biology & life history

• Arrangement and morphology of mesenteries & muscles

• Size, shape & distribution of nematocysts

Why does it matter?

• Variation in biology and/or role in ecosystem

• Repeatability and comparability of results

Biodiversity in Oman

• Components of the tropical Indo-Pacific fauna

• New species (possibly endemic)

• Lacking representatives of Acontiaria

Omani Anemones

A new species of Heteractis?

Anthopleura —biogeography and evolution in the intertidal

zone

• What role do history, geography, or habitat play in

– loss or re-acquisition of asexual reproduction?

– loss, change, or re-acquisition of photosymbionts?

Global Diversity of Edwardsiidae

• Small burrowing anemones

• Poorly known, difficult to collect

Known Distribution

Morphology

Variability

Systematics

of the sea anemone family Actinodendridae

General - morphology

secondary branches

primary branch

column

pedal disc

10 mm

long, highly branched tentacles

Morphology - acrospheres

+ simple, pointed

+ bilobed, narrow

+ bilobed, wide

+ simple, capitate

Actinostephanus haeckeli

Actinodendron arboreum

species complex

Actinodendron alcyonoideum

Megalactis sp.

Stinging capsules

acrosphere

fired capsule

General - habitat

among rocks and corals

on sand

on mud

on sea grass bed

shallow water

General - distribution

+ tropical + Indian and Pacific Ocean and the Red Sea

over 400 records

Variability

+ morphology of tentacles

+ color and color patterns

+ nematocysts (stinging capsules)

Field research helps to understand variability

Variability - morphology

Variant with long: tentacles, branches, acrospheres

elongated tentacle

contracted tentacle

Actinodendron arboreum

Variability - morphology

Variant with short: tentacles, branches, acrospheres

Actinodendron arboreum

Variability with age

+ number of branches increases with age

+ acrospheres are longer in juvenile individuals

Actinodendron arboreum

juvenile adult

Variability with behavior

primary branch

secondary branch

tertiary branch

Actinodendron arboreum

Variability - regeneration of tentacles

normal secondary branches

regenerated secondary branches

Actinodendron alcyonoideum(Quoy and Gaimard, 1833)

original description vsspecimen fromFiji, near Dravuni Isl.

Taxonomy - original descriptions versus reality

CORALLIMORPHARIA

Ha-Rim Cha

The Natural History Museum and Biodiversity Research Center The University of Kansas

Lawrence, KS, USA

Vincent B. Hargreaves

Adorian Ardelean George Miller

CorallimorphariaCorallimorpharia• One of six orders of Zoantharia

• Coral-like sea anemones

• Solitary or colonial polyps without skeleton

• Current Classification: four families, 13 genera, and 50 species

• Widely distributed: from tropical to polar areas and from shallow to

deep water

• Questions in the classification and the phylogenetic relationships

LeRoy (http://www.garf.org)

What do they look like?• Plate-like body

Family Ricordeidae Watzl, 1922

Family Discosomatidae Duchassaing de Fombressin and Michelotti, 1864

(Photos by Vincent B. Hargreaves)

• Cylindrical body

Family Sideractiidae Danielssen, 1890

Family Corallimorphidae Hertwig, 1882

What do they look like?

Corallimorpharia from Red SeaEilat Reef, Israel

Rhodactis rhodostoma

Discosoma unguja

Discosoma nummiforme

(photos by Baraka Kuguru)

Predictive Range Modeling Discosoma nummiforme

SST_mean_monthly, SST_min_max_range, Salinity_ann_avg, Chlora, Tides