- February 23
), a Fellow of Lincoln College, Oxford
, was a marine biologist
who was one of the first to study the functional biology of marine invertebrate larvae
. His best known works on marine larvae were his poems which were published together after his death as Larval Forms and Other Zoological Verses
, which describe the form and function of several marine larvae as well as illustrate some of the controversies of evolutionary biology of the time. Garstang was known for his vehement opposition to Ernst Haeckel's Biogenetic Law
, now discredited. Garstang is also noted for his hypothesis on chordate evolution, known as Garstang's theory, which suggests an alternative route for chordate evolution from echinoderms.
Walter Garstang was born on February 9
as the eldest son of Dr. Walter Garstang of Blackburn and his wife Matilda Mary Wardley, and older brother of the archaeologist John Garstang
. In 1884 at the age of 16, he was awarded a scholarship to Jesus College
at the University of Oxford
and was initially going to study medicine. Under the guidance of Henry Nottidge Moseley
, he joined the school of Zoology, and graduated in 1888 at the age of 20. Before graduation, Garstang was offered a position as secretary and assistant to Gilbert C. Bourne
, the new resident director of the Marine Biological Association
. There he met Ray Lankester
. In 1891 he left Plymouth and was a Berkley
Research Fellow under Milnes Marshall
at Owens College
. A year later, Garstang returned to Plymouth as Assistant Naturalist
, only to be elected a Fellow of Lincoln College, Oxford
, in 1893. In 1894, While Ray Lankester
was the Linacre Chair, he became a professor at Lincoln College, and in 1895 he started the series of Easter classes, in which he took students on week long field courses to Plymouth. The concept of Easter classes was copied at many other schools, and is now considered one of the key courses in any zoologist's training.
Walter Garstang noted after extensively studying marine animals that both echinoderms and chordates are deuterostomes (in which the blastopore forms the anus), while most other possible ancestors of Chordates are protostomes (the blastopore forms the mouth). This inspired Garstang to suggest an alternate route of evolution: from echinoderms to chordates.
There are, of course, many important differences between chordates and echinoderms which must be noted and not ignored. Most importantly, adult echinoderms show little likeness to chordates: echinoderms are radially symmetric, possess calcium carbonate plates in their skin and have tube feet. Garstang made the radical suggestion that perhaps the echinoderm larvae, not adults, had given rise to chordates.
Echinoderm larvae, like chordates, are bilaterally symmetric, and show other shared characteristics with chordates. Especially notable are their similarities to larvae of hemichordates, not true chordates, but rather a step closer to chordates (hemichordates share two of the five most commonly noted chordate characteristics--a hollow dorsal nerve tube and pharyngeal slits).
Garstang's idea has been expanded and is supported by many lines of evidence. Perhaps most interesting and compelling is the fact that some amphibians can stay in larval form and still reach sexual maturity--this shows that echinoderm larvae could, theoretically, have become sexually mature and simply stopped morphing into adults and instead could have evolved into chordate ancestors. Species that show this refusal to leave the larval stage include mud puppies and other salamanders, which either partially or completely show pedomorphism (retention of juvenile traits or phenotypes after sexual maturity).
Garstang's Theory is often overlooked, but was revolutionary for both its time and idea: it suggests that not only may single species evolve, but that single life stages of species may evolve into separate organisms. The theory, which Garstang proposed in the early 20th century, seemed far-fetched at the time of its conception and did not receive support until further research had been done after Garstang's death.
Larval Forms and other zoological verses
First published in 1951, two years after his death, Larval Forms and Other Zoological Verses
is a compilation of Garstang's poems on the form, function and development of various larval invertebrates. Although they were published posthumously, Garstang had had a desire to publish them for many years and never did because he always thought he would add to them. Except for the introduction written by Sir Alister Hardy
, everything in the final publication, including the title and order of the poems, was his own work. The poems included in his final word are:
- The Amphiblastula and the Origin of Sponges
- The Invaginate Gastrula and the Planula
- The Origin of Cnidoblasts and Cnidozoa
- Conaria and Co.
- Mülleria and the Ctenophore
- The Onchosphere
- The Trochophores
- Mitraria's Fan Dance
- The Ballad fo the Veliger, or How the Gastropod got its Twist
- Echinospira's Double Shell
- The Nauplius and the Protaspis
- Isopod Phylogeny
- The Millipede's Egg-tooth
- The Trilobites and After
- Echinoderm Larvae and the Origin of Quinqueradial Symmetry
- The Pentacrinule
- Tornaria's Water-Works
- Oikopleura, Jelly-builder
- The Ancestry of Vertebrates
- Leptocephalus brevirostris, the Larva of the Eel
- The Axolotl and the Ammocoete
- An Oceanographer's Dream
- To a Herring Gull
Of these poems, The Ballad of the Veliger may be his best known work. Many of his poems were written to express his views on the scientific theories of the time. Most notable may be The Axolotl and the Ammocoete which speculates an evolutionary relationship between the Axolotl and the Ammocoete. Alister Hardy wrote on this in the Introduction to Larval Forms:
Only a few months before he died Garstang had drafted a communication toNature to put forward his latest suggestion that Amphioxus might be regarded as a paedomorphic ammocoete-like larva of a Cyclostome; it was never sent, because the day on which he was to have posted it he found that the whole of his idea had recently and quite independently been published by the great Stensio.
The great Stensio referred to here was Erik Stensiö, a Swedish paleozoologist.
The Ballad of the Veliger
This, his most famous poem, was first published in 1928, privately printed, and copies were handed out at the BA meeting that year where Garstang gave the Presidential Address to the Zoology section.
- The Ballad of the Veliger or
How the gastropod got its twist
The Veliger's a lively tar, the liveliest afloat,
A whirling wheel on either side propels his little boat;
But when the danger signal warns his bustling submarine,
He stops the engine, shuts the port, and drops below unseen
He's witnessed several changes in pelagic motor-craft;
The first he sailed was just a tub, with a tiny cabin aft.
An Archi-mollusk fashioned it, according to his kind,
He'd always stowed his gills and things in a mantle-sac behind.
Young Archi-mollusks went to sea with nothing but a velum—
A sort of autocycling hoop, instead of pram—to wheel 'em;
And, spinning round, they one by one acquired parental features,
A shell above, a foot below—the queerest little creatures.
But when by chance they brushed against their neighbours in the briny,
Coelenterates with stinging threads and Arthropods so spiny,
By one weak spot betrayed, alas, they fell an easy prey—
Their soft preoral lobes in front could not be tucked away!
Their feet, you see, amidships, next the cuddy-hole shaft,
Drew in at once, and left their heads exposed to every shaft.
So Archi-mollusks dwindled, and the race was sinking fast,
When by the merest accident salvation came at last.
A fleet of fry turned out one day, eventful in the sequel:
Whose left and right retractors on the two sides were unequal:
Their starboard halliards fixed astern alone supplied the head,
While those set aport were spread abeam and served the back instead.
Predaceous foes, still drifting by in numbers unabated,
Were baffled now by tactics which their dining plans frustrated.
Their prey upon alarm collapsed, but promptly turned about,
With the tender moral safe within and the horny foot without!
This manoeuvre (fide Lamark) speeded up with repetition,
Until the parts affected gained a rhythmical condition,
And torsion, needing now no more a stimulating stab,
Will take its predetermined course in a watchglass in the lab.
In this way, then, the Veliger, triumphantly askew,
Acquired his cabin for'ard, holding all his sailing crew—
A Trochophore in armour cased. with a foot to work the hatch,
And double screws to drive ahead with smartness and despatch.
But when the first new Veligers came home again to shore,
And settled down as Gastropods with mantle-sac afore,
The Archi-mollusk sought a cleft his shame and grief to hide,
Crunched horribly his horny teeth, gave up the ghost, and died.