CHAPTER 15
Animals of the Benthic Environment
Distribution of benthic organisms
Fig. 15.1

More benthic productivity beneath areas of high surface
primary productivity
 Mainly on continental shelves
 Affected by surface ocean currents
www.portfolio.mvm.ed.ac.uk/studentwebs/session2
Benthic organisms on rocky
shores

Epifauna (upon)
 Attached to substrate (e.g.,
marine algae)
 Move on/over seafloor (e.g.,
crabs, snails)

Moderate diversity of
species
 Greatest animal diversity at
tropical latitudes
 Greatest algae diversity at
mid-latitudes (greater
availability of nutrients due
to lack of permanent
thermocline in mid-lats)
http://dnr.metrokc.gov/wlr/waterres
Intertidal
zonation
(rocky
shore)
Fig. 15.2 a
Intertidal zonation (rocky
shore)

Fig. 15.2b
Spray zone
(supratidal)
 Avoid drying out
Monterey Bay, CA
 Many animals have
shells
 Few species of
marine algae
www.mbari.org/staff/conn/botany/methods
http://www.woodbridge.tased.edu.au/mdc/Species%20Register/Barnacle-Tetra.jpg
Intertidal zonation (rocky
shore)

High tide zone
 Avoid drying out so
animals have shells
 Marine algae—rock
weeds with thick cell
walls
http://www.ecology.org/ecophoto/algae/Thumbnails/Plant%20Images-10360.jpg
Intertidal zonation
(rocky shore)

http://www.dfw.state.or.us/mrp/shellfish/commercial/Images/flat_abalone.jpg
Abalone
Middle tide zone
 More types of marine algae
 Soft-bodied animals
Pisaster – sea star,
mussel predator
http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/Mollusca/Bivalvia/Mytiloida/Mytilidae/Pisaster%20Predate%20mussels.jpg
http://www.fisherycrisis.com/chondrus/fig32.JPG
Intertidal zonation
(rocky shore)

Low tide zone
 Abundant algae
 Many animals hidden by
sea weed and sea grass
 Crabs abundant in all
intertidal zones
http://bivalves.info/Donax_hanleyanus.jpg
Benthic organisms on sediment-covered
shores


Similar intertidal zones
Less species diversity
 Greater number of organisms
 Mostly infauna – burrow into
sediment

Microbial communities
Coquina with valves extended
Coquina (Donax)
http://www.theseashore.org.uk/theseashore/Resources%20for%20seashoreweb/Images%20for%20New%20Pages/Donax.JPG
Intertidal zonation (sandy shore)
Fig. 15.8
Benthic organisms on sediment-covered
shores

Energy level along shore depends on
 Wave strength
 Longshore current strength

Wave/current energy determines
habitat…





Coarse boulder beaches
Sand beaches
Salt marshes
Mud flats
Fine-grained, flat-lying tidal flat more stable
than high energy sandy beach
Sandy beaches
Mole crab
Animals burrow
 Bivalve mollusks
 Annelid worms
 Crustaceans
 Echinoderms
 Meiofauna

Ghost crab hiding
Fig. 15-9
http://photography.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/Photography/Images/POD/g/ghost-crab-hiding-760340-sw.jpg
http://www.weeksbay.org/photo_gallery/shorebirds/SEMIPALMATED%20PLOVER.jpg
Mud flats
Eelgrass and turtle grass
common
 Bivalves and other mollusks
 Fiddler crabs

http://www.sms.si.edu/irlspec/images/06PhotoContest/06DeWolfeH3.jpg
http://www.lacoast.gov/articles/bms/1/3_mud_flat_ground_view.jpg
http://www.teara.govt.nz/NR/rdonlyres/ED9A6951-7B98-4AD2-A6A0-CA633137BE7C/74562/p4595doc.jpg
Shallow ocean floor
Continental shelf
 Mainly sediment covered
 Kelp forest associated with rocky
seafloor

 Also lobsters
 Oysters
http://www.lifesci.ucsb.edu/~c_white/images/Lobsters%20in%20San%20Diego.JPG
http://www.ianskipworth.com/photo
/pcd1742/kelp_forest_15_4.jpg
Figure 15.14a,b
Figure 15.14c
Figure 15.16
http://wdfw.wa.gov/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=10996&g2_serialNumber=4
http://www.h2o-mag.com/issue6/images_issue6/coral-01-copy.jpg
Coral reefs
Most coral polyps live in large
colonies
 Hard calcium carbonate
structures cemented together
by coralline algae

www.gettankedaquariums.com
www.mpm.edu/images
Coral reefs

Coral reefs limited to
 Warm (but not hot) seawater
 Sunlight (for symbiotic algae)
 Strong waves or currents
 Clear seawater
 Normal salinity
 Hard substrate
http://www.ee.bilkent.edu.tr/~aytur/pg
www.waterfrontchattanooga.com/Newsroom/High_res
Reef-building corals
Fig. 15-17
Symbiosis of coral and algae
Coral reefs made of algae, mollusks, foraminifers
as well as corals
 Hermatypic coral mutualistic relationship with
algae – zooxanthellae
Soft coral polyp (Lobophytum
 Algae provide food
compactum). Green shows the
 Corals provide nutrients
polyp tissue, while the red

shows the zooxanthellae.
www.bigelow.org/reefwatch2001/coral_reefs/images
http://www.reefed.edu.au/explorer/images
Coral reef zonation

Different types of corals at different depths
Fig. 15.19
http://www.sheppardsoftware.com/images/Oceania/factfile/GreatBarrierReef-EO.jpg
Importance of coral reefs

Largest structures
created by living
organisms
 Great Barrier Reef,
Australia, more than 2000
km (1250 m) long
Great diversity of species
 Important tourist locales
 Fisheries
 Reefs protect shorelines

Great Barrier Reef
from space
Humans and coral reefs


Activities such as fishing, tourist
collecting, sediment influx due to
shore development harm coral
reefs
Sewage discharge and
agricultural fertilizers increase
nutrients in reef waters
Coral covered with macroalgae
 Hermatypic corals thrive at low
nutrient levels
 Phytoplankton overwhelm at high
nutrient levels
 Bioerosion of coral reef by algaeeating organisms
http://daac.gsfc.nasa.gov/oceancolor/images/coral_reef_algae.jpg
○
Other problems

Smoothering by
dredging, runoff
 Fishing practices,
harvesting
 Pollution
 Global warming
http://images.wri.org
Large vs. small reef fish: Fishery management regulations such as
minimum sizes allow fishermen to keep only the largest fish. As shown by
the red snapper example, the largest fish produce the most eggs. One
24-inch red snapper produces the same number of eggs as 212 17-inch
red snapper. So, by selectively removing the largest fish, the fishery
removes the fish that have the greatest potential for producing more fish.
ttp://oceanexplorer.noaa.gov/explorations/02sab/logs/aug05/media
Crown-of-thorns starfish and reefs
Sea star eats
coral polyps
 Outbreaks
(greatly
increased
numbers)
decimate reefs

Fig. 15.21
Worm Reefs
• Sabellariid worms (Phragmatopoma
caudata) form shallow reefs
• St. Augustine to south end of
Biscayne Bay
• Provide habitat for many organisms
www.floridaoceanographic.org/environ/images
www.stlucieco.gov/erd/threatened-endangered






Adult worms (3/4 - 2 in. long) build reefs on limestone and
coquina formations, jetties
Build sand hoods over tubes to reduce desiccation at low tide.
Protective tubes made of sand, joined to neighbors to build
rigid, wave resistant structures.
15,000 to 60,000 worms per m2
Live up to 10½ years.
Thais (oyster drill) is an important predator
http://www.amnh.org/nationalcenter/expeditions/blacksmokers/images/large/amnh19_18.jpg
Benthic organisms on the
deep seafloor

Little known habitat – only
accessable via dredge and
some submersibles and ROVs

Bathyal, abyssal, hadal zones
 Little to no sunlight
 About the same temperature
 About the same salinity
 Oxygen content relatively high
 Pressure can be enormous
 Bottom currents usually slow
http://library.thinkquest.org/17297/images/alvin.gif
http://www.whoi.edu/science/B/people/sbeaulieu/rad_patch_by_mound.jpg
Food sources in deep seafloor
Most food sinks from surface waters
 Low supply and “patchy”

Fig. 15.22
http://i.treehugger.com/images/2007/10/24/deep-sea%20hydrothermal%20vent-jj-001.jpg
Deep-sea hydrothermal vent
biocommunities




First discovered 1977
Chemosynthesis
Archaea use sea floor
chemicals to make
organic matter
Unique communities
 Tube worms
 Giant clams and
mussels
 Crabs
 Microbial mats
www.jamstec.go.jp/jamstec/organi/GOIN
Figure 15.27

Chemosynthesis
 Archaea use sea floor chemicals to make organic
matter
Figure 15.25b
Global hydrothermal vent fields
Fig. 15.24
Deep-sea hydrothermal vent
biocommunities
Vents active for years or decades
 Animals species similar at widely separated
vents
 Larvae drift from site to site
 “Dead whale hypothesis”

○
“Dead whale hypothesis” – Dispersal of vent organisms
 Pelagic eggs/larvae disperse to other food patches or
vent fields
- Methane-bearing springs on continental shelves and
slopes are more common than originally thought
- Possible dispersal to carcasses – support vent
organisms
- Take years to decompose
- Use as "stepping stones
Whale carcass with
worms, sea cucumbers
www.mbari.org
On whale bones, only the pinkish trunk of this cross-section of a female
Osedax tubeworm is visible. The white blobs are ovaries where more than
100 dwarf male tubeworms can live inside the female. Symbiotic bacteria
give the tubeworm's roots their greenish color. Bacteria in the roots of
Osedax produce nutrients by processing the fats and lipids in the bones
of whales.
www.geotimes.org/aug04
Figure 15.C
Fish carcass
On ocean
floor
Figure 15.C 1
Deep-sea hydrothermal vent
biocommunities
Life may have originated at hydrothermal
vents
 Chemosynthesis also occurs at low
temperature seeps

 Hypersaline seeps
 Hydrocarbon seeps
 Subduction zone seeps
Figure 15.28 & 15.29
Figure 15.29b
http://oceanworld.tamu.edu/resources/oceanography-book/Images/Azam-(1998)-2.gif
Beneath the sea floor

Deep biosphere
 Microbes live in porous sea floor
 Might represent much of Earth’s total biomass
In may 2008, prokaryotes were
reported in mud cores extracted
from between 860 to 1626 meters
beneath the sea floor off
Newfoundland. Cells were 1001000 fold denser than in terrestrial
cores of similar depth and about 510% of the cells were dividing.
http://environment.newscientist.com/channel/earth/
deep-sea/dn13960-huge-hidden-biomass-livesdeep- beneath-the-oceans.html