This document summarizes a study on the seaweed Calliarthron thaliae and how its segmented morphology allows it to survive in wave-exposed intertidal zones. The seaweed has calcified segments connected by flexible joints that allow it to bend when struck by waves, preventing breakage. The study measured the stress-strain properties of the joints and performed bend-to-break tests on fronds by clamping and adding incremental masses until breakage. The morphology of Calliarthron thaliae, with its ability to bend at the joints, is what enables it to dominate wave-exposed habitats along rocky shores.

1. +
To break a coraline: mechanical constraints
on the size and survival of a wave-swept
seaweed
Patrick T. Martone and Mark W. Denny
Hopkins Marine Station of Stanford University, Pacific Groove, CA
Presentation by: Wilden Abreu &Lennyn Velez

2. Introduction
oCoraline alga Calliarthronthrives in
wave-exposed intertidal habitats.
oAbility to survive depends on its
segmented morphology
oCalcified
segments, allows for bending, but
+ produces stress
oIntertidalzones of rocky shores can
generate water velocities greater than
25ms^-1. (waves) imposing great forces
on inhabitants.
oDrag is the primary wave-induced force
applied to intertidal algae.

3. + oCalliarthronthaliare firmly
calcified but have flexible
When struck
by
waves, frond
joints called genicula, this
s bend
allows the fronds (thallus) to
parallel to its
bend when struck by waves.
solid
surface.
oThe average
Calliarthronfronds can grow
up to 25cm, and can contain Image above
100 genicula, allowing it to demonstrates
genicular cells
dominate wave-exposed
ruptured
habitats
Calliarthronfronds often break near the base and
tend to grow in densely packed clusters.
Introduction: Continued

4. Methods
•Calliarthronfronds
were collected from a low intertidal
reagion in a moderate wave exposed surge channel at
Hopkins Marine Station in Pacific Grove, California.
•Stressstrain curves were generated for one geniculum from
each of the fronds. Each one was loaded in tension using a
tensometer and a video demension analyzer
+
•Bend to break test
•Brndches were removed from each frond by cutting below the
first dichotomy, and the rest of the segments were tested by
clamping.
•The chained segments were girpped by clamps near the first
few genicula and held out horizontally. A second clamp was
placed near the 10thgenicula and masses were hung in 20 and
50 gram increments until the frond broke.

5. +
Bend to Break Test
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