30 SUMMERS OF URCHINS AND LOVE | ANNE VISSER NEY
in an old farmhouse near Delaware Bay. When I
climaxed, I felt swept to the sea where life began:
whisked over the marshes into the Atlantic,
enjoined with ghost crabs on tidal flats, sea trout
in salty creeks, and right whales migrating south
to warmer seas and winter calving grounds.
This was an orgasm to be experienced, not
studied.
Forty-two weeks later, David squirmed in my
arms and my uterus contracted in muscle mem-
ory. I believed he was mine, not the son of Life’s
longing for itself. I lacked a biologist’s sense that
any single child’s life is inconsequential as long as
enough children survive to the next generation
and secure the future of H. sapiens.
I began thinking in those terms when Dave was
two and I returned to college to study biology.
One year later, doctors discovered the brain
tumor caused by a mutation he was either born
with or acquired early in life. When he was five,
the brother he longed for was stillborn; nobody
understood why the fetus died. At six, David
completed cancer treatments, and I returned
to graduate school to study sea urchin larval
behavior.v. u r c h i n s
Sea urchins are heavily studied as a proxy for
human fertilization and development. They are
easily spawned in vitro as they release their gam-
etes when injected with potassium chloride. Like
humans, their eggs are many times larger than
their flagellated sperm and are surrounded by a
glycoprotein envelope—an urchin’s vitelline, a
human’s zona pellucida. The first sperm to breach
this envelope triggers a chain reaction, the slow
block, which causes the envelope to balloon away
from the ovum, barring entry to all other suitors.
An urchin slow block generally takes less than
sixty seconds and is visible under a microscope: a
fertilized egg floating like a tiny ringed Saturn in
a saltwater universe.
The new zygote cleaves into two identical
cells, then four, eight, and so on. Soon, the cells
differentiate into three germ layers: endoderm,
mesoderm, and ectoderm, destined to become
gut, muscle, and nervous tissues. From this point,
urchin and human developmental pathways
diverge.A day or two after fertilization, urchin zygotes
are free-swimming and self-feeding larvae that
will metamorphose into juvenile adult form after
five to ten weeks. In contrast, a human embryo
implants in the mother’s uterine wall to be
nourished by the placenta for roughly thirty-nine
weeks. Urchins reach reproductive maturity a
mere two years post-fertilization; humans, only
after more than a decade of development.
Urchins produce myriad young, arising from
astronomically high numbers of gametes and
promiscuous reproduction. Humans produce
precious few offspring, who are heavily reliant on
parental support.
An urchin colony sheds gametes directly
into the sea, nearly simultaneously, to increase
fertilization odds. During spawning, the color-
ful emulsion of eggs—my urchins’ were blood
red—and white sperm swirl from the seabed like
an opaque cloud of possibilities. For urchins, sex
is simply a means to a reproductive end.
Humans conflate love and sex, and, while they
are related, they are also utterly different. Sex
moves our DNA into the next generation’s gene
pool.
But I think love offers immortality.vi. neurogenesis
Urchins and other echinoderms—sea stars, sea
lilies, and sea cucumbers—lack a brain although
their well-developed nerve rings perceive light,
touch, temperature, orientation, and water qual-
ity (salinity, for example).
Humans have a well-developed central nervous
system (CNS). Our sexuality likely resides in the
cerebrum, along with cognition and language.
The cerebellum, behind and below it, coordinates
movement and equilibrium. The brainstem, atop
the spinal cord, regulates heartbeat, breathing,
blood pressure, and other autonomic functions,
like vomiting. As well, nerve signals between
the brain and body go through the stem as they
rush along the body’s highways, ferrying sense,
thought, feeling, and response. The entire CNS is
bathed by cerebrospinal fluid that passes through
the fourth ventricle, a slim cavity between the
brainstem and cerebellum, as it circulates.
In both species, the nervous system develops
through neurogenesis, a process under genetic