Obituary Notice: Deep-Ocean Scientist Robert Hessler

Robert "Bob" Hessler, a scientist at Scripps Institution of Oceanography at UC San Diego who revealed the deep oceans to be a place of rich and complex biodiversity, died Oct. 17 at a hospice care facility in Douglas, Ariz. He was 87.

Over a career of more than 40 years, Hessler upended notions that the deep oceans were largely incapable of supporting rich marine life. He was among the first to identify previously unknown forms of life with the ability to survive in some of the harshest conditions on Earth.

“Bob Hessler’s career at Scripps transformed the institution into an internationally-recognized center of research in deep-sea biology,” said Art Yayanos, an emeritus professor in residence of microbiology at Scripps Oceanography, who credited Hessler with providing the foundation for his own research in deep-ocean biology. “Bob’s pioneering work attracted students and collaborators from all over the world. He generously shared his knowledge and was a highly valued mentor to students and colleagues alike.”

Colleagues and former students remembered Hessler not only for his pioneering discoveries, but for his experimental methods for collecting and retrieving marine specimens using instruments improvised for that purpose. Several also noted that Hessler was a champion of his students, who learned from him lessons about character as much as about science.

“Bob Hessler was one of the true greats in the field of deep-sea biology,” said Scripps biological oceanographer Lisa Levin, who nominated him for the Distinguished Teaching Award with which UC San Diego presented him in 1999.  “He leaves a legacy of major scientific discoveries, remarkable teaching and influential students who propelled the field of deep-ocean science into the 21st century.” 

Levin added that her own interest in the deep sea can be traced directly back to Hessler’s deep-sea biology course at Scripps which Levin now co-teaches with biological oceanographer Anela Choy. 

After life was discovered at hydrothermal vents in 1977, Hessler took part in the first biological expedition to one such vent in the Galapagos Rift in 1979. There he identified creatures that can thrive despite the caustic environment around the vents. 

Robert Hessler (right) is introduced to Emperor Hirohito of Japan at Scripps Oceanography in 1975
Robert Hessler (right) is introduced to Emperor Hirohito of Japan at Scripps Oceanography in 1975. The emperor was himself an amateur marine biologist especially interested in crustaceans.

Hessler was born in Chicago, Ill., on November 22, 1932. He studied forestry at Colorado A&M College, Fort Collins, in 1950, and then attended the University of Chicago from 1951 to 1960, where he received an AB in liberal arts in 1953, and MS in zoology in 1955, and a PhD in invertebrate paleontology in 1960.

Hessler was a research associate, assistant scientist, and associate scientist from 1960 to 1968 at Woods Hole Oceanographic Institution. It was there that he engaged in pioneering research with colleague Howard Sanders, using seafloor-scraping sleds to document the abundance of life at depths up to 4,700 meters (15,400 feet). In January 1969, he became an associate professor in the Biological Oceanography Curricular Group and Marine Biology Research Division at Scripps Oceanography. He was promoted to full professor of biological oceanography in 1974. He served as director of the Marine Biology Research Division from 1978 to 1983. He retired in 2001.

The author or coauthor of more than 130 papers on marine biology and ecology, Hessler’s research specialties included the study of marine arthropods (invertebrate animals with articulate bodies and limbs, such as insects, arachnids, and crustaceans) and the ecology of deep-sea bottom communities, including hydrothermal vents and areas targeted for deep-sea manganese nodule mining. His work contributed to knowledge of the systematics, evolution, and functional morphology of arthropods and a greater understanding of the ecology and biodiversity of deep-sea ecosystems.

Besides his work at the Galapagos Rift, Hessler also explored life at other deep-ocean spreading centers including locations off Baja California, one in the Guaymas Basin in the Gulf of California and the other at the East Pacific Rise. These spreading centers are active volcanic sites where new seafloor is being produced. 

Cecelia and Robert Hessler with "Bobby Ray," the deep-ocean vehicle named in Robert Hessler's honor in 2006
Cecelia and Robert Hessler with "Bobby Ray,"
the deep-ocean vehicle named in Robert
Hessler's honor in 2006

Hessler’s studies of the ecology of deep-sea communities also included Scripps’s Eurydice Expedition to the Philippine Trench in 1975, when Hessler’s group successfully photographed life at a depth of 9,600 meters (31,500 feet) with Scripps-developed free-vehicle cameras and took bottom samples with a box corer to obtain quantitative measurements of deep-sea animal communities.

Hessler was a fellow of the American Association for the Advancement of Science and the San Diego Society of Natural History, and a member of a number of scientific organizations, including the American Society of Limnology and Oceanography, the Western Society of Naturalists, the Danish Natural History Society. He was an elected member of the Royal Physiographical Society of Lund, Sweden, where he had also done research while on sabbatical at the University of Lund.

Hessler is survived by wife Cecilia of San Diego and two cousins. His family plans no memorial service.  At his request, his ashes will be commingled with those of his only child, son David, who was killed in 1995 at the age of 30. Those wishing to make gifts in Hessler’s memory are encouraged to make them to Hope Hospice and Health Care.





There are two very important life lessons from Bob that will always stay with me and have shaped my way of advising students. First, and foremost, he always encouraged our independence in choosing our thesis project, he supported our work in as many ways as he could, and he pushed us to be the best. It's true he could be harsh and rough around the edges at times but if you dug down a little, you could see it was done to make you succeed. We were not a cog in a lab machine but rather independent researchers; this is why his legacy of students is so amazing.

Second, he did everything in his power to provide us opportunities to learn what it's like to be a professor, to be a leader, to be a fully developed professional. For me, this meant giving me opportunities to (1) learn how to be an editor for important journals (with minimal supervision), (2) be a leader on research cruises or submersible dives (i.e. we were part of the team and not just graduate students), and (3) to explore other research projects to expand my skills and even to have opportunities to teach. Bob saw that my natural abilities and greatest strengths were in teaching and he was proud of me when I pursued that track rather than the more prestigious (and typical) post-SIO research track. I am a better mentor and advisor because of Bob.

  • Michel Boudrias, associate professor in Environmental and Ocean Sciences and director of the Care for Our Common Home Strategic Pathway at University of San Diego


Hessler’s seminal contributions to ocean trench research were cited by the UK’s Cambridge University Press, in their text, “Deep-Sea Biology: A Natural History of Organisms at the Deep-Sea Floor” (1999). The authors wrote, in part, “From the days of the ‘HMS Challenger’ expedition, biological oceanographers had relied on intuition that the extreme physical conditions and impoverished nutritional input of ocean trenches could be tolerated only by a small number of specialized forms of life. Robert Hessler and Howard Sanders at the Woods Hole Oceanographic Institution overturned this concept in the 1960s after examination of bottom samples obtained by new devices. They revealed an astonishing richness in species of the smaller animals dwelling in the deep-sea sediments, and proved the trend of decreasing diversity with increasing depth was an artifact of the coarse methods used to collect samples heretofore.”  Hessler, who moved to Scripps, and Sanders, who remained at WHOI, dominated research into the ecology and biodiversity of deep-sea benthic life through the 1970s. At Scripps, Hessler collaborated with Professor John Isaacs on development of untethered free fall/free ascent ocean landers. Those early ocean landers carried samplers to collect sediments, animals, and near bottom seawater, while cameras, made from military surplus aircraft nose cameras, filmed seafloor marine life and their behaviors. Scripps Professor Richard Rosenblatt contributed input to the positioning of the cameras for better identification of species. Hessler’s work inspired later generations of engineers and scientists around the world, and still does to this day.


In 2006, Scripps engineers and scientists honored Bob Hessler by naming a new trench-rated ocean lander after him. He laughed, and said, “Well, if you’re going to name it after me, call it ‘Bobby Ray’ like they called me when I was a kid.” Deep Ocean Vehicle, DOV Bobby Ray, made its first dives to the deepest spot in the Atlantic Ocean, in the Puerto Rico Trench, a few months later.

  • Kevin Hardy, senior development engineer, Scripps Institution of Oceanography at UC San Diego (retired)

Bob Hessler was a world authority on various crustacean groups that have low diversity, but were important in understanding crustacean evolution. These included Cephalocarida and Mystacocarida. His work on their taxonomy and anatomy contained after his retirement, until relatively recently. He was honored in having a series of species of Crustacea, Mollusca and Annelida named after him. In recognition of his work in documenting western pacific hydrothermal vents the iconic snail Alvinoconcha hessleri bears his name and locally off La Jolla is the abundant crustacean Nebalia hessleri.

  • Greg Rouse, marine biologist, Scripps Institution of Oceanography at UC San Diego

Bob Hessler’s career at SIO transformed the institution into an internationally recognized center of research in deep-sea biology. Bob’s pioneering work attracted students and collaborators from all over the world. He generously shared his knowledge and was a highly valued mentor to students and colleagues alike. His course in Deep-Sea Biology covered, in an analytical fashion, topics of both historical and contemporary interest. He opened many areas in deep-sea research ranging from systematics and quantitative sampling to the biology of trenches and of hydrothermal vents. He led several deep-sea expeditions on which he was an active participant in the sampling program. On a personal note, his work with John Isaacs and Eric Shulenberger in the early 1970s provided the foundation for my work in deep-sea biology. Bob and I were together on two expeditions. The most memorable for me was Expedition Eurydice to the Philippine Trench in 1975. Bob was the Chief Scientist and had invited notable deep-sea scientists from around the world such as John Allen, Torben Wolff, Fred Grassle and Howard Sanders. Several of his students were also members of the scientific party.

In his later years Bob returned to a passion he had to be an artist. His creative sculptures and paintings are superb and reflect the same attention to perfection and detail that he brought to his science and teaching.

It has been a great singular pleasure and honor to have known Bob Hessler as a colleague and friend.

  • Art Yayanos, emeritus professor in residence of microbiology, Scripps Institution of Oceanography at UC San Diego


About Scripps Oceanography

Scripps Institution of Oceanography at the University of California San Diego is one of the world’s most important centers for global earth science research and education. In its second century of discovery, Scripps scientists work to understand and protect the planet, and investigate our oceans, Earth, and atmosphere to find solutions to our greatest environmental challenges. Scripps offers unparalleled education and training for the next generation of scientific and environmental leaders through its undergraduate, master’s and doctoral programs. The institution also operates a fleet of four oceanographic research vessels, and is home to Birch Aquarium at Scripps, the public exploration center that welcomes 500,000 visitors each year.

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