Australian Bryozoa Volume 1: Biology, Ecology and Natural History

201 Pages·2018·25.37 MB·English

by  Patricia Cook

Australian
BRYOZOA
Volume 1
Biology, Ecology and Natural History
Editors: Patricia L. Cook, Philip E. Bock, Dennis P. Gordon and Haylee J. Weaver
Australian
BryozoA
Volume 1
Biology, Ecology and Natural History
Editors:
Patricia L. Cook, Philip E. Bock, Dennis P. Gordon and Haylee J. Weaver
© Commonwealth of Australia 2018
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Front cover: Celleporaria spp. on a wharf pile (photo: K. Gowlett-Holmes)
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Volume 1 to be cited as:
Cook PL, Bock PE, Gordon DP and Weaver HJ (eds) (2018) Australian Bryozoa Volume 1: Biology, Ecology and
Natural History. CSIRO Publishing, Melbourne.
Individual chapters cited as:
Bock PE, Cook PL and Gordon DP (2018) General morphology and terminology. In Cook PL, Bock PE,
Gordon DP and Weaver HJ (eds) Australian Bryozoa Volume 1: Biology, Ecology and Natural History.
pp. xx–xx. CSIRO Publishing, Melbourne.
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Contents
List of authors v
1 Introducing bryozoans 1
Patricia L. Cook, Dennis P. Gordon, Peter J. Hayward, Philip E. Bock and Yvonne Bone
1.1 Introduction 1
1.2 Phylogeny and classification 2
1.3 Ecology of bryozoans 5
1.4 Economic significance 10
References 11
2 History of discovery in Australian waters 17
Philip E. Bock, Patricia L. Cook and Dennis P. Gordon
2.1 Introduction 17
2.2 Early collections: 1700s and 1800s 17
2.3 Collecting in the 1900s 21
2.4 Bryozoa to the present, and current status of collecting 22
References 23
3 General morphology and terminology 29
Philip E. Bock, Patricia L. Cook and Dennis P. Gordon
3.1 External characteristics and astogeny 29
3.2 Skeletal system 31
3.3 Colonial tropisms, kineses and mobility 33
3.4 Feeding and digestive system 34
3.5 Interzooidal communications and the funicular system 36
3.6 Respiration and excretion 38
3.7 Degeneration and regeneration cycles 38
3.8 Nervous system and sense organs 39
3.9 Glandular systems 40
3.10 Reproduction 40
3.11 Genetic studies 45
References 47
4 Modern and Cenozoic bryozoan colony classification schemes 55
Yvonne Bone
4.1 Introduction 55
4.2 Examples of bryozoan growth forms 56
4.3 Substratum and attachment 61
4.4 Conclusion 62
Acknowledgements 63
References 63
5 Bryozoans on seamounts 65
Dennis P. Gordon
5.1 Introduction 65
5.2 Australian seamounts 65
5.3 Bryozoans on Australian and New Zealand seamounts 66
References 68
iv AustrAliAn BryozoA
6 Bryozoans and biosecurity 71
Dennis P. Gordon
6.1 Introduction 71
6.2 Bryozoans as marine-fouling organisms 71
6.3 Alien bryozoans in Australia 73
6.4 Conclusion 84
References 84
Colour plates 91
7 Bryozoans and biotechnology 121
Michèle Prinsep
7.1 Introduction 121
7.2 Compounds isolated from bryozoans 122
7.3 Compounds used against bryozoans 131
7.4 Conclusion 132
References 132
8 Bryozoans and ocean acidification 139
Abigail M. Smith
8.1 Ocean acidification: an old, but new global problem 139
8.2 What can we do about acidification? 140
8.3 Bryozoans as potential allies 140
8.4 Bryozoans as ‘canaries’ 140
8.5 Bryozoan growth models 141
8.6 Bryozoans as sentinels 142
8.7 Conclusion 142
References 143
9 Bryozoans in the marine benthos 145
Robyn L. Cumming, Dennis P. Gordon and Karen Gowlett-Holmes
9.1 Introduction 145
9.2 Temperate benthic environments 146
9.3. Tropical benthic environments 150
9.4. Environmental correlates 156
9.5. Bryozoans as habitat 157
Acknowledgements 157
References 158
10 Fossil bryozoans of Australia
section A – Palaeozoic era 163
Catherine M. Reid
A10.1 Introduction 163
A10.2 Class Stenolaemata (range Ordovician to Recent) 163
A10.3 Class Gymnolaemata (range Ordovician to Recent) 164
section B – Mesozoic–Cenozoic eras 165
Rolf Schmidt
B10.1 Mesozoic 165
B10.2 Cenozoic 165
References 167
Glossary 171
Index 177
LIst oF A utHors
Philip E. Bock Peter J. Hayward
Museum Victoria, Melbourne, Victoria 3001, School of Biological Sciences, University of Wales,
Australia Swansea, United Kingdom
Yvonne Bone Michèle Prinsep
School of Earth and Environmental Sciences, Uni- School of Science, University of Waikato, Hamilton
versity of Adelaide, Adelaide, South Australia 5005, 3240, New Zealand
Australia
Catherine M. Reid
Patricia L. Cook (deceased) Department of Geological Sciences, University of
Glen Waverley, Victoria 3150, Australia Canterbury, Christchurch 8140, New Zealand
Robyn L. Cumming Rolf Schmidt
Museum of Tropical Queensland, Townsville, Museum Victoria, Melbourne, Victoria 3001,
Queensland 4810, Australia Australia
Dennis P. Gordon Abigail M. Smith
National Institute of Water and Atmospheric Department of Marine Science, University of Otago,
Research, Wellington 6021, New Zealand Dunedin 9054, New Zealand
Karen Gowlett-Holmes
CSIRO Marine Laboratories, Hobart, Tasmania
7000, Australia
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1
Introducing bryozoans
Patricia L. Cook, Dennis P. Gordon, Peter J. Hayward,
Philip E. Bock and Yvonne Bone
1.1 Introduction growth, some living species in shallow coastal
water or on the present-day continental shelf form
Bryozoans are aquatic animals that form colonies
important seafloor habitat for a variety of other
of connected individuals. Bryozoans have such
highly variable morphology that they are often organisms including economically important fish
mistaken for other organisms such as hydroids, and shellfish. Some species have shown promise as
corals, colonial ascidians and turfing seaweeds. sources of marine natural products such as anti-
Some colonies are bushy and moss-like, hence the cancer, antiviral and antifouling substances.
phylum name, Bryozoa, which means ‘moss ani- Bryozoa are aquatic and mostly marine, with
mals’ in Greek. Others are flat and encrusting, species found in all oceans from sublittoral to abys-
hence the common name ‘sea mats’. Still others sal depths. Freshwater species inhabit high mon-
resemble lace, forming erect frondose colonies with tane lakes, and ponds, streams and rivers in all
holes in their structure or encrustations over sea- continents except Antarctica. More than 6300 living
weeds and rocks, hence the name ‘lace corals’. Since species (WoRMS Editorial Board 2017) and 15 000
no single common name is applicable to all species, fossil species have been described. Including
the name ‘bryozoans’ is the one most preferred by known but undescribed species, the Australian
researchers of the group. fauna currently stands at around 1200 species: the
Bryozoans have long had a reputation for being highest for any country in the world. This figure,
a minor, sometimes unimportant phylum, but they however, is highly conservative and it is likely that
are by no means rare. In some habitats they are the the Australian fauna includes well over 2000 spe-
dominant organisms. Some species foul boat bot- cies. The group has a long fossil history, beginning
toms and ship hulls, marinas, pontoons, wharf in the earliest Ordovician; both past and present
piles and even reticulation systems of marine and faunas are highly abundant and diverse.
freshwater installations. Because they can settle on Each bryozoan colony (sometimes referred to by
vessels, some bryozoan species are important alien palaeontologists as the zoarium – the fossil skeletal
invasives. Other species can be abundant on some expression of the colony) is a series of clones of tiny
parts of the continental shelf and, over geological genetically identical members called zooids, which
time, their shelly remains, along with molluscan may be highly varied in size and shape. Each
shell and the carbonate remains of other organ- colony begins as a single zooid, the ancestrula,
isms, have been fossilised into limestone forma- which forms when a larva settles on substrata and
tions that now outcrop on land. With their robust metamorphoses. The ancestrula buds off daughter
2 AustrAliAn BryozoA
zooids, which in turn bud additional zooids until known as polymorphs), and their forms and func-
the colony reaches its optimum size. Depending on tions vary widely within and between species,
species, a mature colony may have only two or genera and families. Heterozooid form is com-
three, or many millions of zooids, and as a result monly used to define taxa, at every taxonomic
may range in size from less than 1 mm to more level, despite a growing appreciation of the adap-
than 1 m. Colonies are usually sessile, developing tive nature of these zooids. Kenozooids are the
from a motile larva by settlement and metamor- simplest type of polymorph. Spines, rhizoids (root-
phosis, and live attached to a substratum such as lets) and some brooding structures are kenozooids.
rock, shell or algae, or wood. They often colonise The term denotes an empty unit – a coelomic cavity
other animals, such as hydroids, gorgonians and bounded by a body wall but lacking a tentacle
other bryozoans. A few forms have rootlet-like crown and orifice. It may be similar in shape and
rhizoids that anchor them directly into the sedi- size to an autozooid, or radically different from it.
ment, and others are unattached, living intersti- Size, shape, and function vary continuously among
tially in the surface layers. Some unattached species structures defined as kenozooids; homologies
are capable of motility: ‘walking’ or lurching by the between these are not always clear, and the devel-
aid of bristle-like structures on the colony opmental processes giving rise to them are not
periphery. always predictable.
Most bryozoans have a calcareous skeleton,
except for the members of the freshwater class Phy-
1.2 Phylogeny and classification
lactolaemata and the mostly marine Ctenostomata
(class Gymnolaemata), which have non-calcified Bryozoans have certainly been known to European
colonies. Colonies are hermaphrodite, although naturalists for more than 450 years (Wyse Jackson
individual zooids may contain either ovaries or and Spencer Jones 2002), yet, interestingly, the
testes, or both, or neither. All bryozoans are sus- wider relationships of the phylum are as puzzling
pension feeders, capturing small living and non- in the 21st century as they were in the 18th century
living particles from water. Accordingly, most (see Box 1.1). Although there is emerging consen-
zooids in a colony are feeding zooids, called auto- sus based on gene sequencing and molecular data,
zooids. Each autozooid has an eversible bell-shaped controversy still remains. The animal nature of
cluster of ciliated tentacles (the tentacle crown) bryozoans was suggested by Peyssonnel (Watson
that entrap food particles. The mouth is situated at 1751–52; Peyssonnel 1756) and others, but was not
the base of the circlet of tentacles and leads to a generally accepted until the publication of the Nat-
U-shaped digestive tract; the anus opens exterior to ural History of the Corallines by Ellis in 1755. Lin-
the base of the tentacle crown (Plate 1.1). The organs naeus (1758) included them with coelenterates in
and tissues in an autozooid that undergo periodic Zoophyta (‘animal-plants’), considering them to be
replacement – namely, tentacles, tentacle sheath, partly of a plant nature. The discovery that bryozo-
alimentary canal, associated musculature and ans had a tubular gut, with a mouth and anus, as
nerve ganglion – are collectively termed a polypide well as ciliated tentacles, eventually led to their
(Hayward and Ryland 1979). separation from coelenterates as Polyzoa (‘many
The colonies of many species are highly poly- animals’) by Thompson (1830) and Bryozoa (‘moss
morphic (meaning ‘many forms’), having a variety animals’) by Ehrenberg (1831) (see Box 1.2). Milne
of non-feeding zooids that exhibit a range of form Edwards (1843) grouped bryozoans with molluscs
and function. These other types of zooids may sup- and tunicates as Molluscoidea – an assemblage to
port the autozooids, or be budded in distinctive which brachiopods were later added – and this
patterns on or among them. Collectively, all poly- concept, in part at least, extended into the 20th
morphic zooids are termed heterozooids (also century.
1 – IntroducIng bryozoans 3
Box 1.1. Bryozoa by another name
Historically, bryozoans were confused with other organisms and, owing to the plant-like appearance of
some, were considered among the ‘zoophytes’ (literally ‘animal-plants’) of the early naturalists. Other
phylum names have been applied to Bryozoa. For example, Polyzoa (‘many animals’, referring to the colonies
of a few to millions of individuals) was once commonly used in Britain and Australasia. The name was
introduced by the English naturalist J.V. Thompson in 1830 – a year earlier than German scientist Gottfried
Ehrenberg (1831) introduced Bryozoa – but rules of nomenclatural priority do not apply to higher taxa.
Ectoprocta (which alludes to the fact that the anus opens outside the ring of tentacles, in contradistinction to
Entoprocta) and Entoprocta were introduced as subdivisions of Bryozoa by Heinrich Nitsche in 1869. Each
was elevated to a phylum by Hatschek (1888). Europeans and North Americans have traditionally used the
name Bryozoa and this was the name formally accepted by the International Bryozoology Association when
the association was inaugurated in 1965 (Cheetham 2002). Unfortunately, the late Libbie Hyman (1959),
author of a highly authoritative series of books on the invertebrates, resurrected the name Ectoprocta. Since
Hyman’s work, some influential textbooks in the United States resulted in the perpetuation of this name,
which has now been superseded in favour of Bryozoa (Nielsen 2012; Ruggiero et al. 2015).
Box 1.2. Place in the animal kingdom
Bryozoans are protostomes (Greek, protos, first, stoma, mouth). Technically, a protostome is an animal
in which the first opening in the embryo becomes the mouth – present in flatworms, molluscs, annelids
and arthropods. However, this feature can be equivocal in bryozoans, owing to the particular mode of
embryonic development. Currently, as indicated by nucleic acid sequencing, as well as some anatomical
and embryological studies, bryozoans are classified among the Lophotrochozoa (Spiralia), that sub-branch
of the Protostomia that includes segmented worms, molluscs, brachiopods and their kin, to the exclusion of
the moulting animals (Ecdysozoa): that is, insects, crustaceans and other arthropods, plus nematode worms
and related small phyla. The precise relationships of Bryozoa within the Lophotrochozoa are still unclear,
however. Several molecular studies have segregated them from Brachiopoda (lamp shells) and Phoronida
(horseshoe worms), with which they had earlier been grouped based on several morphological criteria, and
allied them instead with Entoprocta and Cycliophora. Nesnidal et al. (2013) have recovered a Lophophorata
clade that re-unites bryozoans with the other ‘lophophorate’ groups based on molecular criteria, but, as
Nielsen (2012) has pointed out, whereas Brachiopoda and Phoronida have monociliated epithelial cells,
those of Bryozoa are multiciliated. This is a non-trivial distinction and the question of close relationship
remains open.
This history of nomenclature nevertheless gives pointed out that, whereas brachiopods and phoro-
an indication of the various other phyla to which nids have monociliated epidermal cells, bryozoans
bryozoans have been deemed to be related on mor- have multiciliated epidermal cells – a phylogeneti-
phological grounds. One persuasive arrangement cally significant feature. Moreover, the mode of
has been that of Lophophorata (Hatschek 1888; beating of ciliary tracts for suspension feeding is
Hyman 1959), uniting Bryozoa, Brachiopoda and downstream-collecting in Bryozoa and upstream-
Phoronida on the basis of a structurally similar collecting in Brachiopoda and Phoronida. These,
feeding apparatus (the tentacle crown) deemed to and other embryological characteristics, united bra-
be homologous, along with a perceived tripartite chiopods and phoronids with core deuterostomes
body plan. In his comprehensive morphological (echinoderms, hemichordates, tunicates and chor-
analysis of the animal kingdom, Nielsen (1995) dates) and allied bryozoans with Entoprocta in