Marine Animals I
Marine Animals I. The Invertebrates
OCN 201 Biology Lecture 6
Illustration : Ernst Haeckel
Arthropods Segmented Worms The Animal Vertebrates
Family Tree Mollusks
Echinoderms Round Worms
Cnidarians
Bilateria
PlacozoaNo symmetry Sponges Ancestral Protist
)]
that
that
27
” ”
RESEARCH ARTICLE ArthropodsM. leidyi EST Set RESEARCH ARTICLE “ Segmented
SUMMARY Genome Set
“ Worms
Vertebrates SpizellomycesM. leidyi punctatus Batrachochytrium dendrobatidis Cryptococcus neoformans READ THE FULL ARTICLE ONLINE Saccharomyces cerevisiae Phycomyces blakesleeanus The Genome of the Ctenophore http://dx.doi.org/10.1126/science.1242592 )] methods. To understand the Rhizopus orizae Outgroup Amoebidiumet parasiticum al 28 Citeramoredetaileddescriptionofthe this article as J. F. Ryan ., Science 342, 1242592 (2013).Sphaeroforma arctica Mnemiopsis leidyi and Its Implications Capsaspora_owczarzaki DOI: 10.1126/science.1242592 Monosiga ovata Salpingoeca rosettamodel as implemented in RAxML ( for Cell Type Evolution 72 Monosiga brevicollisG Pleurobrachia pileus Mnemiopsis leidyi We found no support in any of these analyses
embryo shown oral side down. Embryos are about Ctenophora
ment of Ctenophora as sister group to all other
Maximum-likelihood analyses support the place-
of Placozoa, Cnidaria, and Bilateria (Tr,Cn,Bi).
Cnidaria and Bilateria (Cn,Bi) and for a clade
broad support for a sister relationship between
animals (Tr,) (Table 1 and fig. S1). We recovered
Mertensiid sp Placozoa being the sister lineage to the rest of
for Coelenterata (Cn,Ct), Diploblastica (Bi,), or
Joseph F. Ryan, Kevin Pang, Christine E. Schnitzler, Anh-Dao Nguyen, R. Travis Moreland, atotalof16analyses(Table1).
od and matrix. This multifactorial strategy yielded
outgroups (table S11) in each combination of meth-
ogy, we included four different sets of nonmetazoan
effect of outgroup selection on our ingroup topol-
in PhyloBayes (
and Bayesian [with the CAT model as implemented
GTR+
matrices by using maximum-likelihood [with the
animals, 64.9% missing data). We analyzed both
nldsprilgnmcdata genomic partial includes from many taxa (58
mals, 19.6% missing data) and an
includes only data from complete genomes (13 ani-
and fraction of missing data: a
matrices that differ in breadth of taxon sampling
of gene sequence evolution. We assessed two data
sampling used in previous phylogenomic analyses
has allowed us to improve on the ctenophore The availability of the complete genome of Phylogenetic Position of Leucetta chagosensis David K. Simmons, Bernard J. Koch, Warren R. Francis, Paul Havlak, FIGURES IN THE FULL ARTICLE Sycon raphanus 88 NISC Comparative Sequencing Program, Stephen A. Smith, Nicholas H. Putnam, Oscarella carmela Porifera
Fig. 1.M. leidyi M. leidyi life history and anatomy.
Steven H. D. Haddock, Casey W. Dunn, Tyra G. Wolfsberg, James C. Mullikin, 77 Oscarella lobularis
Tr
Po
Ct Cn Bi Oopsacas minuta Mark Q. Martindale, Andreas D. Baxevanis* Fig. 2. Previously98 proposed relationshipsCarteriospongia foliascens
97 Amphimedon queenslandica www.sciencemag.org of the fi ve deep clades of animals. Suberites domuncula 96 (Bi,) Lubomirskia baicalensis Fig. 3. Tree produced by maximum-likelihood
Ephydatia muelleri)Ctenophoraas Introduction: An understanding of ctenophore biology is critical for reconstructing events that The label at the
analysis96 of the EST set. B genome is low to m. See the supplementary materials fo Trichoplax adhaerens
occurred early in animal evolution. The phylogenetic relationship of ctenophores (comb jellies) to m Placozoa
Fig. 4. Tree produced by maximum-likelihoodCyanea capillata
Tr
Po
Ct Cn
other animals has been a source of long-standing debate. Until recently, it was thought that Porif- Bi Clytia hemisphaerica
SCIENCE
ctenophore body plan. [Photo credit for (A): courtesy of Bruno Vellutini] 200
(Science, Dec 2013) Later development of Hydra magnipapillata analysis of gene content. transcript is 5.8 kb. Eight
era (sponges) was the earliest diverging animal lineage, but recent reports have instead suggested 96 Podocoryna carnea Cnidaria M. leidyi Ctenophora as the earliest diverging animal lineage. Because ctenophores share some of the same Fig. 5. The origin) of postsynaptic genes.Hydractinia echinata
Nematostella(Tr,) vectensis M complex cell types with bilaterians (such as neural and mesodermal cells), the phylogenetic position 82 Anemonia viridis Fig. 6. Inventoryto of myogenic components
)One- Aiptasia pallida J M. leidyi
of ctenophores affects how we think about the early evolution of these cell types. )Ctenophoraassistergrouptothe
D Metridium senile D
in M. leidyi. )Diploblasticahypothesis.Weseeno
Methods: We have sequenced, annotated, and analyzed the 150-megabase genome of the cteno- Acropora palmata F
Ct
Po
Tr Cn Bi Acropora millepora phore Mnemiopsis leidyi. We have performed detailed phylogenetic analyses on these new data SUPPLEMENTARY(about 10 cm MATERIALS Porites astreoides Montastraea faveolata
using both sequence matrices and information on gene content. We conducted extensive genomic )Coelenteratahypothesis.( Xenoturbella bocki Materials and Methods A inventories on signaling pathway components and genes known to be critical to neural and meso- 45 Nemertoderma westbladi Meara stichopi
Figs. S1M. leidyi to S10
tables S5 to S10.
characteristics of this genome are presented in
end and mate-pair sequencing alone. Additional
high-quality genome assembly based on paired-
S3 and S4); this has made it possible to produce a
moderate, as compared to other metazoans (tables
tive sequence in the
alternatively expressed exons. The level of repeti- A), (E), and (F) and very little support for (B) (see
may be inflated owing to a subset of these being
is high compared to other genomes (table S2), but
other genes. This number of nested intronic genes
percent of predicted genes are embedded within of an unspliced dermal cell types, among others. 98 groups with non-ctenophores. The average length
)Gastrulastage.( Isodiametra pulchra Tables S1 to S31I Symsagittifera roscoffensis
Results: Our phylogenetic analyses suggest that ctenophores are the sister group to the rest of the References Convolutriloba longifissura
)Adult
Po
Ct
Tr Cn extant animals. We fi nd that the sets of neural components present in the genomes of Mnemiopsis Bi Saccoglossus kowalevskii
A Ptychodera flava ( and the sponge Amphimedon queenslandica are quite similar, suggesting that sponges have the Strongylocentrotus purpuratus
necessary genetic machinery for a functioning nervous system but may have lost these cell types. 44 Asterina pectinifera )andis
Branchiostoma floridae 26 13 DECEMBER 2013 VOL 342 We also fi nd that, although Mnemiopsis has most of the genes coding for structural components of )Aboralviewofcydippidstage.( 83 Petromyzon marinus C Gallus gallus
mesodermal cells, they lack many of the genes involved in bilaterian mesodermal specifi cation and, BilateriaGenome = 100 bootstrap Ciona intestinalis therefore, may have independently evolved these cell types. support Halocynthia roretzi
43 ), was 98.2%. In
Po
Tr
Cn Ct The phylogenetic positionBi of the ctenophoreEchinoderes horni )Earlycleavagestages.( 88 Xiphinema index
Discussion: These results present a newly supported view of early animal evolution that accounts Mnemiopsis leidyiH 94and its implications regarding
Euperipatoides kanangrensis to
for major losses and/or gains of sophisticated cell types, including nerve and muscle cells. This0.2 the origin of mesodermal99 cell types. (AAnoplodactylus) Adult eroticus M. leidyi E 99 evolutionary framework, along with the comprehensive genomic resources made available through M. leidyi. (B) Summary of the relationships of the fiBoophilus ve microplus Daphnia pulex
main branches of animals and the outgroup Choano- )PoriferaassistergrouptotherestofMetazoa.(
this study, will yield myriad discoveries about our most distant animal relatives, many of which will 93 Drosophila melanogaster
C
)PlacozoaassistergrouptotherestofMetazoa.( fl a g e l l a tlifea history and . anatomy. ( C) Inventory of myogenic specifi cation shed light not only on the biology of these extant organisms but also on the evolutionary history of E Schmidtea mediterranea
genes in Mnemiopsis. Components present in the Paraplanocera oligoglena genome is among the smallest 7%
Po
Tr
Ct Cn Capitella telata all animal species, including our own. Mnemiopsis genome95 are inBi blue, and names are Helobdella robusta underlined. Absent components84 are in red. CerebratulusThe lack of lacteus
85 M. leidyi many of these)Close-upviewofcombrows.( factors in Mnemiopsis indicatesTerebratalia that transversa
B 44 Euprymna scolopes ctenophore mesodermal cell types are specifi ed differ- M. leidyi Lottia(Cn,Ct) gigantea (Ct,Bi) (Po,) (Ct,)
ently than in bilaterians, suggesting that they perhapsCrassostrea virginica
sign 44% of these gene predictions into homology
up 58% of the genome, and we conservatively as-
16,548 predicted protein-coding loci, which make
densely packed with gene sequences. It encodes AB C D E F
in the Animal Genome Size Database (
of genomes when compared with those cataloged
The
Characteristics of the
assembled.
the assembly is both complete and accurately
to a single scaffold. These numbers suggest that
94.8% of cases, a single EST mapped completely
as determined by baa.pl25 (
Table 1). Ct, Ctenophora; Po, Porifera; Tr, Placozoa; Cn, Cnidaria; Bi, Bilateria.
support in any of our analyses for the hypotheses in (
rest of Metazoa. (
sister to Bilateria. (
evolved independently in these two lineages. bottom of each pane corresponds to the header of Table 1. (
Fig. 2. Previously proposed of relationships the five deep clades of animals.
celled fertilized embryo. (
long). (
Fig. 1. 1242592-2 Fig. 3. Tree produced by maximum-likelihood analysis of the EST Set. The tree was produced from a matrix consisting of 242 genes and 104,840 amino A B acidCnidaria characters. Circles on nodesC indicate 100% bootstrap support. Support placing ctenophores as sister to the rest of Metazoa is 96% of 100 bootstrap
RESEARCH ARTICLE FGF replicates. BMPs/dpp Shh/hh Bilateria 1242592-4 13 DECEMBER 2013 VOLNK2 342 SCIENCE www.sciencemag.org Wnt/Wg Noggin s Placozoa u GATA le c Twist u Eomes n Lbx Porifera MyoG Mef2 Slp NK3 Snail Mrf4 Ctenophora Eya Six1/4 Myf5 MyoD Choanoflagellata Gli NK4
The list of author affi liations is available in the full article online. *Corresponding author. E-mail: [email protected] Arthropods 1336 13 DECEMBER 2013 VOL 342 SCIENCE www.sciencemag.org Segmented Published by AAAS Worms The Animal Vertebrates
Family Tree Mollusks
Echinoderms Round Worms
Cnidarians Text
Bilateria
)]
that
that
27
”
”
M. leidyi
EST Set
“
Genome Set
“
M. leidyi
)] methods. To understand the
28
ramoredetaileddescriptionofthe
model as implemented in RAxML (
G
We found no support in any of these analyses
embryo shown oral side down. Embryos are about
ment of Ctenophora as sister group to all other
Maximum-likelihood analyses support the place-
of Placozoa, Cnidaria, and Bilateria (Tr,Cn,Bi).
Cnidaria and Bilateria (Cn,Bi) and for a clade
broad support for a sister relationship between
animals (Tr,) (Table 1 and fig. S1). We recovered
Placozoa being the sister lineage to the rest of
for Coelenterata (Cn,Ct), Diploblastica (Bi,), or
atotalof16analyses(Table1).
od and matrix. This multifactorial strategy yielded
outgroups (table S11) in each combination of meth-
ogy, we included four different sets of nonmetazoan
effect of outgroup selection on our ingroup topol-
in PhyloBayes (
and Bayesian [with the CAT model as implemented
GTR+
matrices by using maximum-likelihood [with the
animals, 64.9% missing data). We analyzed both
nldsprilgnmcdata genomic partial includes from many taxa (58
mals, 19.6% missing data) and an
includes only data from complete genomes (13 ani-
and fraction of missing data: a
matrices that differ in breadth of taxon sampling
of gene sequence evolution. We assessed two data
sampling used in previous phylogenomic analyses
has allowed us to improve on the ctenophore
The availability of the complete genome of Phylogenetic Position of
M. leidyi Radiata
Tr
Po
Ct Cn
Ctenophores Bi www.sciencemag.org
(Bi,) Flatworms
)Ctenophoraas
The label at the
B
genome is low to
m. See the supplementary materials fo
m
Tr
Po
Ct
Cn
Bi
SCIENCE
ctenophore body plan. [Photo credit for (A): courtesy of Bruno Vellutini]
200
Later development of
transcript is 5.8 kb. Eight
M. leidyi
)
(Tr,)
M
to
)One-
J
M. leidyi
)Ctenophoraassistergrouptothe
D
D
)Diploblasticahypothesis.Weseeno
F
Ct
Po
Tr
Cn
Bi
(about 10 cm )Coelenteratahypothesis.(
A No symmetry
M. leidyi
tables S5 to S10.
characteristics of this genome are presented in
end and mate-pair sequencing alone. Additional
high-quality genome assembly based on paired-
S3 and S4); this has made it possible to produce a
moderate, as compared to other metazoans (tables
tive sequence in the
alternatively expressed exons. The level of repeti- A), (E), and (F) and very little support for (B) (see
may be inflated owing to a subset of these being
is high compared to other genomes (table S2), but
other genes. This number of nested intronic genes
percent of predicted genes are embedded within
of an unspliced
groups with non-ctenophores. The average length )Gastrulastage.(
I Placozoa
)Adult
Po
Ct
Tr
Cn
Bi A
Sponges(
)andis 26
13 DECEMBER 2013 VOL 342
)Aboralviewofcydippidstage.(
C
Genome
), was 98.2%. In
Po
Tr
Cn Ct
Bi Ancestral
)Earlycleavagestages.(
H
to M. leidyi
ctenophores E
)PoriferaassistergrouptotherestofMetazoa.(
C
)PlacozoaassistergrouptotherestofMetazoa.(
life history and anatomy.
E
genome is among the smallest 7%
Po
Tr
Ct Cn
Bi Protist
M. leidyi
)Close-upviewofcombrows.(
B
M. leidyi
(Cn,Ct) (Ct,Bi) (Po,) (Ct,)
sign 44% of these gene predictions into homology
up 58% of the genome, and we conservatively as-
16,548 predicted protein-coding loci, which make
densely packed with gene sequences. It encodes AB C D E F
in the Animal Genome Size Database (
of genomes when compared with those cataloged
The
Characteristics of the
assembled.
the assembly is both complete and accurately
to a single scaffold. These numbers suggest that
94.8% of cases, a single EST mapped completely
as determined by baa.pl25 (
Table 1). Ct, Ctenophora; Po, Porifera; Tr, Placozoa; Cn, Cnidaria; Bi, Bilateria.
support in any of our analyses for the hypotheses in (
rest of Metazoa. (
sister to Bilateria. (
bottom of each pane corresponds to the header of Table 1. (
Fig. 2. Previously proposed of relationships the five deep clades of animals.
celled fertilized embryo. (
long). (
Fig. 1.
1242592-2 RESEARCH ARTICLE Invertebrate Phyla • Placozoa • Porifera (sponges) • Cnidarians (jellyfish, corals, hydroids) • Ctenophores (comb jellies) • Flat Worms • Round Worms • Molluscs (clams, snails, squid, octopi) • Segmented Worms • Arthropods (copepods, crabs, shrimp) • Echinoderms (sea stars, brittle stars)
Placozoa
• Simplest animal? • Lacks symmetry • Only four cell types • No tissues or organs • Found on surfaces • Probably feeds on surface algae and bacteria • Can fold itself to create a digestive pocket Porifera (sponges)
• “Skeleton” may be calcareous or silica spicules, or entirely of the protein collagen • Benthic -- intertidal to abyssal, all latitudes • Suspension Feeders (strain plankton, bacteria. A few exceptions) • Large range of cell types, lack of tissue types • Source of many bioactive compounds
Diversity in size & shape, Many growth forms
MBARI Sponge Skeletons Glass sponge ( Venus’ Flower Calcareous Sponge Basket) Natural Sponge
collagen
Sponge Anatomy
choanocyte Arthropods Segmented Worms The Animal Vertebrates
Family Tree Mollusks
Echinoderms Round Worms
Cnidarians
Bilateria
Ctenophores Radiata Flatworms
Placozoa Sponges Ancestral Protist
Ctenophores (comb jellies) Ctenophores (comb jellies)
Ctenophores (comb jellies) • Earliest branching metazoan phylum? • All are marine • Pelagic from 0 to >3000 m (few benthic creepers) • Have eight rows of cilia (comb rows) • Carnivorous • Use tentacles with sticky colloblasts • Some directly ingest prey (Beroe)
)]
that
that
27
”
”
M. leidyi
EST Set
“
Genome Set
“
M. leidyi
)] methods. To understand the
28
ramoredetaileddescriptionofthe
model as implemented in RAxML (
G
We found no support in any of these analyses
embryo shown oral side down. Embryos are about
ment of Ctenophora as sister group to all other
Maximum-likelihood analyses support the place-
of Placozoa, Cnidaria, and Bilateria (Tr,Cn,Bi).
Cnidaria and Bilateria (Cn,Bi) and for a clade
broad support for a sister relationship between
animals (Tr,) (Table 1 and fig. S1). We recovered
Placozoa being the sister lineage to the rest of
for Coelenterata (Cn,Ct), Diploblastica (Bi,), or
atotalof16analyses(Table1).
od and matrix. This multifactorial strategy yielded
outgroups (table S11) in each combination of meth-
ogy, we included four different sets of nonmetazoan
effect of outgroup selection on our ingroup topol-
in PhyloBayes (
and Bayesian [with the CAT model as implemented
GTR+
matrices by using maximum-likelihood [with the
animals, 64.9% missing data). We analyzed both
nldsprilgnmcdata genomic partial includes from many taxa (58
mals, 19.6% missing data) and an
includes only data from complete genomes (13 ani-
and fraction of missing data: a
matrices that differ in breadth of taxon sampling
of gene sequence evolution. We assessed two data
sampling used in previous phylogenomic analyses
has allowed us to improve on the ctenophore
The availability of the complete genome of
Phylogenetic Position of
M. leidyi
Tr
Po
Ct
Cn
Bi
www.sciencemag.org
(Bi,)
)Ctenophoraas
The label at the
B
genome is low to
m. See the supplementary materials fo
m
Tr
Po
Ct
Cn
Bi
SCIENCE
ctenophore body plan. [Photo credit for (A): courtesy of Bruno Vellutini]
200
Later development of
transcript is 5.8 kb. Eight
M. leidyi
)
(Tr,)
M
to
)One-
J
M. leidyi
)Ctenophoraassistergrouptothe
D
D
)Diploblasticahypothesis.Weseeno
F
Ct
Po
Tr
Cn
Bi
(about 10 cm )Coelenteratahypothesis.(
lobate A
M. leidyi
tables S5 to S10.
characteristics of this genome are presented in
end and mate-pair sequencing alone. Additional
high-quality genome assembly based on paired-
S3 and S4); this has made it possible to produce a
moderate, as compared to other metazoans (tables
tive sequence in the
alternatively expressed exons. The level of repeti- A), (E), and (F) and very little support for (B) (see
may be inflated owing to a subset of these being
is high compared to other genomes (table S2), but
other genes. This number of nested intronic genes
percent of predicted genes are embedded within
of an unspliced
groups with non-ctenophores. The average length
)Gastrulastage.(
I
)Adult
Po
Ct
Tr
Cn
Bi
A
(
)andis 26
13 DECEMBER 2013 VOL 342
)Aboralviewofcydippidstage.(
C
Genome
), was 98.2%. In
Po
Tr
Cn
Ct
Bi
)Earlycleavagestages.(
H
to
M. leidyi
E
)PoriferaassistergrouptotherestofMetazoa.(
C
)PlacozoaassistergrouptotherestofMetazoa.(
life history and anatomy.
E
genome is among the smallest 7%
Po
Tr
Ct
Cn
Bi
M. leidyi
)Close-upviewofcombrows.(
cestid B
M. leidyi
(Cn,Ct) (Ct,Bi) (Po,) (Ct,)
sign 44% of these gene predictions into homology
up 58% of the genome, and we conservatively as-
16,548 predicted protein-coding loci, which make
densely packed with gene sequences. It encodes AB C D E F
in the Animal Genome Size Database (
of genomes when compared with those cataloged
The
Characteristics of the
assembled.
the assembly is both complete and accurately
to a single scaffold. These numbers suggest that
94.8% of cases, a single EST mapped completely
as determined by baa.pl25 (
Table 1). Ct, Ctenophora; Po, Porifera; Tr, Placozoa; Cn, Cnidaria; Bi, Bilateria.
support in any of our analyses for the hypotheses in (
rest of Metazoa. (
sister to Bilateria. (
bottom of each pane corresponds to the header of Table 1. (
Fig. 2. Previously proposed of relationships the five deep clades of animals.
celled fertilized embryo. (
long). (
Fig. 1. 1242592-2
beroe RESEARCH ARTICLE cydippid
Ctenophores Cnidarians (anemones, corals, jellyfish)
• Named for the stinging cells (cnidocytes) • Radial symmetry • Two forms: polyps and medusae (some have alternation of generations) • Asexual and Sexual Reproduction
• Radial symmetry • Simple Digestive system (blind sac) • No circulatory, respiratory or excretory systems Polyp Medusa • carnivores/detritovores • Primitive nerve networks Cnidocytes Cnidocytes
• Prey capture • Turf wars • Defense
toxins
Class Hydrozoa: hydroids and hydromedusae Class Anthozoa: Sea anenomes, corals, sea pens Class Cubozoa: sea wasps and box jellies Class Scyphozoa: jellyfish (big jellies) Jellyfish
Arthropods Segmented Worms The Animal Vertebrates
Family Tree Mollusks
Echinoderms Round Worms
Cnidarians
Bilateria
Ctenophores Radiata Flatworms
Placozoa Sponges Ancestral Protist Flatworms (Platyhelminthes) • Turbellarian flatworms are marine, benthic • Infauna from intertidal to deep sea • Carnivorous or herbivorous • Move by cilia or undulations • Mouth but no anus • Cephalization
Roundworms (Nematodes)
• Flow-through digestive system! • Found all over (terrestrial, freshwater, marine) • VERY abundant free-living in benthic infauna • Many other types are parasitic • Many are deposit feeders, detritivores Arthropods Segmented Worms The Animal Vertebrates
Family Tree Mollusks
Echinoderms Round Worms
Cnidarians
Bilateria
Ctenophores Radiata Flatworms
Placozoa Sponges Ancestral Protist
Molluscs
MAJOR CLASSES • Bivalvia (Clams, oysters, mussels)
• Gastropoda (snails, nudibranchs)
• Cephalopoda (squid, octupus, nautilus) Bivalves Burrowing
• Many burrowing and boring boring • Others attach to rocky surfaces • Suspension feeding or selective deposit feeding
Gastropods
• Many with shells (snails, whelks, etc.) some types without shells (e.g. nudibranchs) • Some planktonic forms (e.g. pteropods) • Herbivores and carnivores, deposit and suspension feeders • Have a radula (a toothed scraper) Cephalopods
• Well developed brains and eyes • Many have ink sacs • Only one type still has external shell (Chambered nautilus) • Carnivores; Have a radula and beak for tearing food • Many can rapidly change colors (camouflage, communication)
Molluscs Arthropods Segmented Worms The Animal Vertebrates
Family Tree Mollusks
Echinoderms Round Worms
Cnidarians
Bilateria
Ctenophores Radiata Flatworms
Placozoa Sponges Ancestral Protist
Segmented Worms (Annelids) • Major Class: the Polychaetes • Mostly benthic, a few planktonic - predatory epifauna
- tube-dwelling infauna (deposit/ suspension feeders) well developed central nervous system Polychaetes
Food capture & Gas Exchange Christmas tree worm
tube dwelling
Arthropoda (jointed foot)
• Exoskeleton (protection, leverage) • Striated Muscle (quick, powerful) • Herbivores, carnivores, omnivores • External Skeleton requires molting Arthropoda: Crustacea
Malacostraca branchiopods
ostracods isopods copepods amphipods
mysids
decapod
Arthropoda
• Vast majority of marine arthropods are crustaceans • Exceptions: marine insects, cheliceriformes (e.g., horseshoe crabs, pycnogonids)
horseshoe crabs
halobates Arthropods
Arthropods Segmented Worms The Animal Vertebrates Family Tree Mollusks
Echinoderms Round Worms
Cnidarians
Bilateria
Ctenophores Radiata Flatworms
Placozoa Sponges Ancestral Protist Echinoderms • Echino derm = spiny skin • Most are suspension or deposit feeders, sea stars also predatory • From intertidal to abyssal depths, nearly all are benthic • Have tube feet • Bilaterally symmetric as larvae, adults pentaradially symmetric
Echinoderms Sea Stars Sea Cucumbers
Sea Urchins Brittle Stars
Crinoids Echinoderms
Questions?